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+
+<body style="display: inherit; "><div class="head"><p></p><h1 class="title" id="title">The JSON-LD API 1.0</h1><h2 id="subtitle">An Application Programming Interface for the JSON-LD Syntax</h2><h2 id="unofficial-draft-16-october-2011">Unofficial Draft 16 October 2011</h2><dl><dt>Editors:</dt><dd><a href="http://manu.sporny.org/">Manu Sporny</a>, <a href="http://digitalbazaar.com/">Digital Bazaar</a></dd>
+<dd><a href="http://greggkellogg.net/">Gregg Kellogg</a>, Kellogg Associates</dd>
+<dd><a href="http://digitalbazaar.com/">Dave Longley</a>, <a href="http://digitalbazaar.com/">Digital Bazaar</a></dd>
+<dt>Authors:</dt><dd><a href="http://digitalbazaar.com/">Dave Longley</a>, <a href="http://digitalbazaar.com/">Digital Bazaar</a></dd>
+<dd><a href="http://digitalbazaar.com/">Manu Sporny</a>, <a href="http://digitalbazaar.com/">Digital Bazaar</a></dd>
+<dd><a href="http://greggkellogg.net/">Gregg Kellogg</a>, Kellogg Associates</dd>
+</dl><p class="copyright">This document is licensed under a <a class="subfoot" href="http://creativecommons.org/licenses/by/3.0/" rel="license">Creative Commons Attribution 3.0 License</a>.</p><hr /></div>
+<div id="abstract" class="introductory section"><h2>Abstract</h2>
+<p>
+JSON [<cite><a class="bibref" rel="biblioentry" href="#bib-RFC4627">RFC4627</a></cite>] has proven to be a highly useful object serialization and
+messaging format. JSON-LD [<cite><a class="bibref" rel="biblioentry" href="#bib-JSON-LD">JSON-LD</a></cite>] harmonizes the representation of
+Linked Data in JSON by outlining a common JSON representation format for
+expressing directed graphs; mixing both Linked Data and non-Linked Data in
+a single document. This document outlines an Application Programming
+Interface and a set of algorithms for programmatically transforming
+JSON-LD documents.
+</p>
+</div><div id="sotd" class="introductory section"><h2>Status of This Document</h2><p>This document is merely a public working draft of a potential specification. It has no official standing of any kind and does not represent the support or consensus of any standards organisation.</p>
+<p>This document is an experimental work in progress.</p>
+
+<!-- <p>
+This document has been reviewed by W3C Members, by software
+developers, and by other W3C groups and interested parties, and is
+endorsed by the Director as a W3C Recommendation. It is a stable
+document and may be used as reference material or cited from another
+document. W3C's role in making the Recommendation is to draw attention
+to the specification and to promote its widespread deployment. This
+enhances the functionality and interoperability of the Web.
+</p> -->
+
+</div><div id="toc" class="section"><h2 class="introductory">Table of Contents</h2><ul class="toc"><li class="tocline"><a href="#introduction" class="tocxref"><span class="secno">1. </span>Introduction</a><ul class="toc"><li class="tocline"><a href="#how-to-read-this-document" class="tocxref"><span class="secno">1.1 </span>How to Read this Document</a></li><li class="tocline"><a href="#contributing" class="tocxref"><span class="secno">1.2 </span>Contributing</a></li></ul></li><li class="tocline"><a href="#the-application-programming-interface" class="tocxref"><span class="secno">2. </span>The Application Programming Interface</a><ul class="toc"><li class="tocline"><a href="#jsonldprocessor" class="tocxref"><span class="secno">2.1 </span>JsonLdProcessor</a><ul class="toc"><li class="tocline"><a href="#methods" class="tocxref"><span class="secno">2.1.1 </span>Methods</a></li></ul></li><li class="tocline"><a href="#jsonldtriplecallback" class="tocxref"><span class="secno">2.2 </span>JsonLdTripleCallback</a><ul class="toc"><li class="tocline"><a href="#methods-1" class="tocxref"><span class="secno">2.2.1 </span>Methods</a></li></ul></li></ul></li><li class="tocline"><a href="#algorithms" class="tocxref"><span class="secno">3. </span>Algorithms</a><ul class="toc"><li class="tocline"><a href="#syntax-tokens-and-keywords" class="tocxref"><span class="secno">3.1 </span>Syntax Tokens and Keywords</a></li><li class="tocline"><a href="#algorithm-terms" class="tocxref"><span class="secno">3.2 </span>Algorithm Terms</a></li><li class="tocline"><a href="#context-1" class="tocxref"><span class="secno">3.3 </span>Context</a><ul class="toc"><li class="tocline"><a href="#coerce" class="tocxref"><span class="secno">3.3.1 </span>Coerce</a></li><li class="tocline"><a href="#initial-context" class="tocxref"><span class="secno">3.3.2 </span>Initial Context</a></li></ul></li><li class="tocline"><a href="#iri-expansion" class="tocxref"><span class="secno">3.4 </span>IRI Expansion</a></li><li class="tocline"><a href="#iri-compaction" class="tocxref"><span class="secno">3.5 </span>IRI Compaction</a></li><li class="tocline"><a href="#value-expansion" class="tocxref"><span class="secno">3.6 </span>Value Expansion</a></li><li class="tocline"><a href="#value-compaction" class="tocxref"><span class="secno">3.7 </span>Value Compaction</a></li><li class="tocline"><a href="#expansion" class="tocxref"><span class="secno">3.8 </span>Expansion</a><ul class="toc"><li class="tocline"><a href="#expansion-algorithm" class="tocxref"><span class="secno">3.8.1 </span>Expansion Algorithm</a></li></ul></li><li class="tocline"><a href="#compaction" class="tocxref"><span class="secno">3.9 </span>Compaction</a><ul class="toc"><li class="tocline"><a href="#compaction-algorithm" class="tocxref"><span class="secno">3.9.1 </span>Compaction Algorithm</a></li></ul></li><li class="tocline"><a href="#framing" class="tocxref"><span class="secno">3.10 </span>Framing</a><ul class="toc"><li class="tocline"><a href="#framing-algorithm-terms" class="tocxref"><span class="secno">3.10.1 </span>Framing Algorithm Terms</a></li><li class="tocline"><a href="#framing-algorithm" class="tocxref"><span class="secno">3.10.2 </span>Framing Algorithm</a></li></ul></li><li class="tocline"><a href="#normalization" class="tocxref"><span class="secno">3.11 </span>Normalization</a><ul class="toc"><li class="tocline"><a href="#normalization-algorithm-terms" class="tocxref"><span class="secno">3.11.1 </span>Normalization Algorithm Terms</a></li><li class="tocline"><a href="#normalization-state" class="tocxref"><span class="secno">3.11.2 </span>Normalization State</a></li><li class="tocline"><a href="#normalization-algorithm" class="tocxref"><span class="secno">3.11.3 </span>Normalization Algorithm</a></li><li class="tocline"><a href="#node-relabeling-algorithm" class="tocxref"><span class="secno">3.11.4 </span>Node Relabeling Algorithm</a></li><li class="tocline"><a href="#deterministic-labeling-algorithm" class="tocxref"><span class="secno">3.11.5 </span>Deterministic Labeling Algorithm</a></li><li class="tocline"><a href="#shallow-comparison-algorithm" class="tocxref"><span class="secno">3.11.6 </span>Shallow Comparison Algorithm</a></li><li class="tocline"><a href="#object-comparison-algorithm" class="tocxref"><span class="secno">3.11.7 </span>Object Comparison Algorithm</a></li><li class="tocline"><a href="#deep-comparison-algorithm" class="tocxref"><span class="secno">3.11.8 </span>Deep Comparison Algorithm</a></li><li class="tocline"><a href="#node-serialization-algorithm" class="tocxref"><span class="secno">3.11.9 </span>Node Serialization Algorithm</a></li><li class="tocline"><a href="#serialization-label-generation-algorithm" class="tocxref"><span class="secno">3.11.10 </span>Serialization Label Generation Algorithm</a></li><li class="tocline"><a href="#combinatorial-serialization-algorithm" class="tocxref"><span class="secno">3.11.11 </span>Combinatorial Serialization Algorithm</a></li><li class="tocline"><a href="#serialization-comparison-algorithm" class="tocxref"><span class="secno">3.11.12 </span>Serialization Comparison Algorithm</a></li><li class="tocline"><a href="#mapping-serialization-algorithm" class="tocxref"><span class="secno">3.11.13 </span>Mapping Serialization Algorithm</a></li><li class="tocline"><a href="#label-serialization-algorithm" class="tocxref"><span class="secno">3.11.14 </span>Label Serialization Algorithm</a></li></ul></li><li class="tocline"><a href="#data-round-tripping" class="tocxref"><span class="secno">3.12 </span>Data Round Tripping</a></li><li class="tocline"><a href="#rdf-conversion" class="tocxref"><span class="secno">3.13 </span>RDF Conversion</a><ul class="toc"><li class="tocline"><a href="#overview" class="tocxref"><span class="secno">3.13.1 </span>Overview</a></li><li class="tocline"><a href="#rdf-conversion-algorithm-terms" class="tocxref"><span class="secno">3.13.2 </span>RDF Conversion Algorithm Terms</a></li><li class="tocline"><a href="#rdf-conversion-algorithm" class="tocxref"><span class="secno">3.13.3 </span>RDF Conversion Algorithm</a></li><li class="tocline"><a href="#acknowledgements" class="tocxref"><span class="secno">3.13.4 </span>Acknowledgements</a></li></ul></li></ul></li><li class="tocline"><a href="#references" class="tocxref"><span class="secno">A. </span>References</a><ul class="toc"><li class="tocline"><a href="#normative-references" class="tocxref"><span class="secno">A.1 </span>Normative references</a></li><li class="tocline"><a href="#informative-references" class="tocxref"><span class="secno">A.2 </span>Informative references</a></li></ul></li></ul></div>
+
+
+
+<div id="introduction" class="section">
+
+<!-- OddPage -->
+<h2><span class="secno">1. </span>Introduction</h2>
+
+<p>
+JSON, as specified in [<cite><a class="bibref" rel="biblioentry" href="#bib-RFC4627">RFC4627</a></cite>], is a simple language for representing
+data on the Web. Linked Data is a technique for creating a graph of interlinked data across
+different
+documents or Web sites. Data entities are described using <a class="tref" title="IRI">IRI</a>s,
+which are typically dereferencable and thus may be used to find more
+information about an entity, creating a "Web of Knowledge". JSON-LD is intended to be a simple
+publishing method for expressing not only Linked Data in JSON, but also for adding
+semantics to existing JSON.
+</p>
+
+<p>
+JSON-LD is designed as a light-weight syntax that can be used to express
+Linked Data. It is primarily intended to be a way to use Linked Data
+in Javascript and other Web-based programming environments. It is also
+useful when building interoperable Web services and when storing Linked
+Data in JSON-based document storage engines. It is practical and designed
+to be as simple as possible, utilizing the large number of JSON parsers
+and libraries available today. It is designed to be able to
+express key-value pairs, RDF data, RDFa [<cite><a class="bibref" rel="biblioentry" href="#bib-RDFA-CORE">RDFA-CORE</a></cite>] data, Microformats
+[<cite><a class="bibref" rel="biblioentry" href="#bib-MICROFORMATS">MICROFORMATS</a></cite>] data, and Microdata [<cite><a class="bibref" rel="biblioentry" href="#bib-MICRODATA">MICRODATA</a></cite>]. That is, it supports
+every major Web-based structured data model in use today.
+</p>
+
+<p>
+The syntax does not necessarily require applications to change their JSON, but
+allows to easily add meaning by adding context in a way that is either in-band or
+out-of-band. The syntax is designed to not disturb already deployed systems
+running on JSON, but provide a smooth upgrade path from JSON to JSON with
+added semantics. Finally, the format is intended to be easy to parse, efficient to
+generate, convertible to RDF in one pass, and require a very small memory footprint
+in order to operate.
+</p>
+
+<div id="how-to-read-this-document" class="section">
+<h3><span class="secno">1.1 </span>How to Read this Document</h3>
+
+<p>
+This document is a detailed specification for a serialization of Linked
+Data in JSON. The document is primarily intended for the following audiences:
+</p>
+
+<ul>
+ <li>Authors that want a very detailed view of how JSON-LD processors
+ operate.</li>
+ <li>Software developers that want to implement processors and APIs for
+ JSON-LD.</li>
+</ul>
+
+<p>
+To understand the basics in this specification you must first be familiar with
+JSON, which is detailed in [<cite><a class="bibref" rel="biblioentry" href="#bib-RFC4627">RFC4627</a></cite>]. You must also understand the
+JSON-LD Syntax [<cite><a class="bibref" rel="biblioentry" href="#bib-JSON-LD">JSON-LD</a></cite>], which is the base syntax used by all of the
+algorithms in this document. To understand the API and how it is
+intended to operate in a programming environment, it is useful to have working
+knowledge of the JavaScript programming language [<cite><a class="bibref" rel="biblioentry" href="#bib-ECMA-262">ECMA-262</a></cite>] and
+WebIDL [<cite><a class="bibref" rel="biblioentry" href="#bib-WEBIDL">WEBIDL</a></cite>]. To understand how JSON-LD maps to RDF, it is helpful to be
+familiar with the basic RDF concepts [<cite><a class="bibref" rel="biblioentry" href="#bib-RDF-CONCEPTS">RDF-CONCEPTS</a></cite>].</p>
+
+<p>
+ Examples may contain references to existing vocabularies and use <a class="tref" title="prefix">prefix</a>es to refer to Web Vocabularies. The following is a list of all vocabularies and their <a class="tref" title="prefix">prefix</a> abbreviations, as used in this document:
+</p>
+<ul>
+ <li>The <a href="http://purl.org/dc/terms/">Dublin Core</a>
+ vocabulary (abbreviation: <code>dc</code>, e.g., <code>dc:title</code>)</li>
+ <li>The <a href="http://xmlns.com/foaf/0.1/">Friend of a Friend</a>
+ vocabulary (abbreviation: <code>foaf</code>, e.g., <code>foaf:knows</code>)</li>
+ <li>The <a href="http://www.w3.org/1999/02/22-rdf-syntax-ns#">RDF</a>
+ vocabulary (abbreviation: <code>rdf</code>, e.g., <code>rdf:type</code>)</li>
+ <li>The <a href="http://www.w3.org/2001/XMLSchema#">XSD</a>
+ vocabulary (abbreviation: <code>xsd</code>, e.g., <code>xsd:integer</code>)</li>
+</ul>
+
+<p>
+ JSON [<cite><a class="bibref" rel="biblioentry" href="#bib-RFC4627">RFC4627</a></cite>] defines several terms which are used throughout this document:
+ </p><dl>
+ <dt><dfn title="JSON_Object" id="dfn-json_object">JSON Object</dfn></dt><dd>
+ An object structure is represented as a pair of curly brackets surrounding zero or
+ more name/value pairs (or members). A name is a <a class="tref internalDFN" title="string" href="#dfn-string">string</a>. A single colon comes after
+ each name, separating the name from the value. A single comma separates a value
+ from a following name. The names within an object <em class="rfc2119" title="should">should</em> be unique.
+ </dd>
+ <dt><dfn title="array" id="dfn-array">array</dfn></dt>
+ <dd>
+ An array is an ordered collection of values. An array structure is represented as square brackets surrounding zero or more values (or elements). Elements are separated by commas. Within JSON-LD, array order is not preserved by default, unless
+ specific markup is provided (see <a href="#lists">Lists</a>). This is because the basic data model of JSON-LD
+ is a directed <a class="tref" title="graph">graph</a>, which is inherently unordered.
+ </dd>
+ <dt><dfn title="string" id="dfn-string">string</dfn></dt><dd>
+ A string is a sequence of zero or more Unicode characters, wrapped in double quotes, using backslash escapes. A
+ character is represented as a single character string.
+ </dd>
+ <dt><dfn title="number" id="dfn-number">number</dfn></dt>
+ <dd>
+ A number is is similar to that used in most programming languages, except that the octal and hexadecimal formats are not used and that leading zeros are not allowed.</dd>
+ <dt><dfn title="true" id="dfn-true">true</dfn> and <dfn title="false" id="dfn-false">false</dfn></dt><dd>
+ Boolean values.
+ </dd>
+ <dt><dfn title="null" id="dfn-null">null</dfn></dt><dd>
+ The use of the <em>null</em> value is undefined within JSON-LD.
+ <div class="issue">Supporting <em>null</em> in JSON-LD might have a number of advantages and should be evaluated. This is currently an <a href="https://github.com/json-ld/json-ld.org/issues/11">open issue</a>.</div>
+ </dd>
+ </dl>
+<p></p>
+</div>
+
+<div id="contributing" class="section">
+<h3><span class="secno">1.2 </span>Contributing</h3>
+
+<p>There are a number of ways that one may participate in the development of
+this specification:</p>
+
+<ul>
+<li>Technical discussion typically occurs on the public mailing list:
+<a href="http://lists.w3.org/Archives/Public/public-linked-json/">public-linked-json@w3.org</a>
+</li>
+
+<li><a href="http://json-ld.org/minutes/">Public teleconferences</a> are held
+on Tuesdays at 1500UTC on the second and fourth week of each month.
+</li>
+
+<li>Specification bugs and issues should be reported in the
+<a href="https://github.com/json-ld/json-ld.org/issues">issue tracker</a>.</li>
+
+<li><a href="https://github.com/json-ld/json-ld.org/tree/master/spec">Source code</a> for the
+specification can be found on Github.</li>
+
+<li>The <a href="http://webchat.freenode.net/?channels=#json-ld">#json-ld</a>
+IRC channel is available for real-time discussion on irc.freenode.net.</li>
+</ul>
+
+</div>
+
+</div>
+
+<div id="the-application-programming-interface" class="section">
+
+<!-- OddPage -->
+<h2><span class="secno">2. </span>The Application Programming Interface</h2>
+
+<p>This API provides a clean mechanism that enables developers to convert
+JSON-LD data into a a variety of output formats that are easier to work with in
+various programming languages. If a JSON-LD API is provided in a programming
+environment, the entirety of the following API <em class="rfc2119" title="must">must</em> be implemented.
+</p>
+
+<div id="jsonldprocessor" class="section">
+<h3><span class="secno">2.1 </span>JsonLdProcessor</h3>
+<pre class="idl"><span class="idlInterface" id="idl-def-JsonLdProcessor">[<span class="extAttr">NoInterfaceObject</span>]
+interface <span class="idlInterfaceID">JsonLdProcessor</span> {
+<span class="idlMethod"> <span class="idlMethType"><a>object</a></span> <span class="idlMethName"><a href="#widl-JsonLdProcessor-expand-object-object-input-object-context">expand</a></span> (<span class="idlParam"><span class="idlParamType"><a>object</a></span> <span class="idlParamName">input</span></span>, <span class="idlParam">optional <span class="idlParamType"><a>object</a>?</span> <span class="idlParamName">context</span></span>) raises (<span class="idlRaises"><a>InvalidContext</a></span>);</span>
+<span class="idlMethod"> <span class="idlMethType"><a>object</a></span> <span class="idlMethName"><a href="#widl-JsonLdProcessor-compact-object-object-input-object-context">compact</a></span> (<span class="idlParam"><span class="idlParamType"><a>object</a></span> <span class="idlParamName">input</span></span>, <span class="idlParam">optional <span class="idlParamType"><a>object</a>?</span> <span class="idlParamName">context</span></span>) raises (<span class="idlRaises"><a>InvalidContext</a></span>, <span class="idlRaises"><a>ProcessingError</a></span>);</span>
+<span class="idlMethod"> <span class="idlMethType"><a>object</a></span> <span class="idlMethName"><a href="#widl-JsonLdProcessor-frame-object-object-input-object-frame-object-options">frame</a></span> (<span class="idlParam"><span class="idlParamType"><a>object</a></span> <span class="idlParamName">input</span></span>, <span class="idlParam"><span class="idlParamType"><a>object</a></span> <span class="idlParamName">frame</span></span>, <span class="idlParam"><span class="idlParamType"><a>object</a></span> <span class="idlParamName">options</span></span>) raises (<span class="idlRaises"><a>InvalidFrame</a></span>);</span>
+<span class="idlMethod"> <span class="idlMethType"><a>object</a></span> <span class="idlMethName"><a href="#widl-JsonLdProcessor-normalize-object-object-input-object-context">normalize</a></span> (<span class="idlParam"><span class="idlParamType"><a>object</a></span> <span class="idlParamName">input</span></span>, <span class="idlParam">optional <span class="idlParamType"><a>object</a>?</span> <span class="idlParamName">context</span></span>) raises (<span class="idlRaises"><a>InvalidContext</a></span>);</span>
+<span class="idlMethod"> <span class="idlMethType"><a>object</a></span> <span class="idlMethName"><a href="#widl-JsonLdProcessor-triples-object-object-input-JsonLdTripleCallback-tripleCallback-object-context">triples</a></span> (<span class="idlParam"><span class="idlParamType"><a>object</a></span> <span class="idlParamName">input</span></span>, <span class="idlParam"><span class="idlParamType"><a href="#idl-def-JsonLdTripleCallback" class="idlType"><code>JsonLdTripleCallback</code></a></span> <span class="idlParamName">tripleCallback</span></span>, <span class="idlParam">optional <span class="idlParamType"><a>object</a>?</span> <span class="idlParamName">context</span></span>) raises (<span class="idlRaises"><a>InvalidContext</a></span>);</span>
+};</span>
+</pre><div id="methods" class="section"><h4><span class="secno">2.1.1 </span>Methods</h4><dl class="methods"><dt id="widl-JsonLdProcessor-compact-object-object-input-object-context"><code>compact</code></dt><dd><a href="#compaction">Compacts</a> the given <code>input</code>
+ according to the steps in the
+ <a href="#compaction-algorithm">Compaction Algorithm</a>. The
+ <code>input</code> <em class="rfc2119" title="must">must</em> be copied, compacted and returned if there are
+ no errors. If the compaction fails, an appropirate exception <em class="rfc2119" title="must">must</em> be
+ thrown.
+
+
+
+
+
+
+ <table class="parameters"><tr><th>Parameter</th><th>Type</th><th>Nullable</th><th>Optional</th><th>Description</th></tr><tr><td class="prmName">input</td><td class="prmType"><code><a>object</a></code></td><td class="prmNullFalse">✘</td><td class="prmOptFalse">✘</td><td class="prmDesc">The JSON-LD object to perform compaction on.</td></tr><tr><td class="prmName">context</td><td class="prmType"><code><a>object</a></code></td><td class="prmNullTrue">✔</td><td class="prmOptTrue">✔</td><td class="prmDesc">The base context to use when compacting the <code>input</code>.</td></tr></table><table class="exceptions"><tr><th>Exception</th><th>Description</th></tr><tr><td class="excName"><a>InvalidContext</a></td><td class="excDesc"><table class="exceptionCodes"><tr><td class="excCodeName"><code>INVALID_SYNTAX</code></td><td class="excCodeDesc">A general syntax error was detected in the <code>@context</code>.
+ For example, if a <code>@coerce</code> key maps to anything other than
+ a string or an array of strings, this exception would be raised.</td></tr><tr><td class="excCodeName"><code>MULTIPLE_DATATYPES</code></td><td class="excCodeDesc">There is more than one target datatype specified for a single
+ property in the list of coercion rules. This means that the processor
+ does not know what the developer intended for the target datatype for a
+ property.</td></tr></table></td></tr><tr><td class="excName"><a>ProcessingError</a></td><td class="excDesc"><table class="exceptionCodes"><tr><td class="excCodeName"><code>LOSSY_COMPACTION</code></td><td class="excCodeDesc">The compaction would lead to a loss of information, such as a
+ <code>@language</code> value.</td></tr><tr><td class="excCodeName"><code>CONFLICTING_DATATYPES</code></td><td class="excCodeDesc">The target datatype specified in the coercion rule and the
+ datatype for the typed literal do not match.</td></tr></table></td></tr></table><div><em>Return type: </em><code><a>object</a></code></div></dd><dt id="widl-JsonLdProcessor-expand-object-object-input-object-context"><code>expand</code></dt><dd><a href="#expansion">Expands</a> the given <code>input</code>
+ according to the steps in the
+ <a href="#expansion-algorithm">Expansion Algorithm</a>. The
+ <code>input</code> <em class="rfc2119" title="must">must</em> be copied, expanded and returned if there are
+ no errors. If the expansion fails, an appropriate exception <em class="rfc2119" title="must">must</em> be thrown.
+
+
+
+
+
+ <table class="parameters"><tr><th>Parameter</th><th>Type</th><th>Nullable</th><th>Optional</th><th>Description</th></tr><tr><td class="prmName">input</td><td class="prmType"><code><a>object</a></code></td><td class="prmNullFalse">✘</td><td class="prmOptFalse">✘</td><td class="prmDesc">The JSON-LD object to copy and perform the expansion upon.</td></tr><tr><td class="prmName">context</td><td class="prmType"><code><a>object</a></code></td><td class="prmNullTrue">✔</td><td class="prmOptTrue">✔</td><td class="prmDesc">An external context to use additionally to the context embedded in <code>input</code> when expanding the <code>input</code>.</td></tr></table><table class="exceptions"><tr><th>Exception</th><th>Description</th></tr><tr><td class="excName"><a>InvalidContext</a></td><td class="excDesc"><table class="exceptionCodes"><tr><td class="excCodeName"><code>INVALID_SYNTAX</code></td><td class="excCodeDesc">A general syntax error was detected in the <code>@context</code>.
+ For example, if a <code>@coerce</code> key maps to anything other than
+ a string or an array of strings, this exception would be raised.</td></tr><tr><td class="excCodeName"><code>MULTIPLE_DATATYPES</code></td><td class="excCodeDesc">There is more than one target datatype specified for a single
+ property in the list of coercion rules. This means that the processor
+ does not know what the developer intended for the target datatype for a
+ property.</td></tr></table></td></tr></table><div><em>Return type: </em><code><a>object</a></code></div></dd><dt id="widl-JsonLdProcessor-frame-object-object-input-object-frame-object-options"><code>frame</code></dt><dd><a href="#framing">Frames</a> the given <code>input</code>
+ using the <code>frame</code> according to the steps in the
+ <a href="#framing-algorithm">Framing Algorithm</a>. The
+ <code>input</code> is used to build the framed output and is returned if
+ there are no errors. If there are no matches for the frame,
+ <code>null</code> <em class="rfc2119" title="must">must</em> be returned. Exceptions <em class="rfc2119" title="must">must</em> be thrown if there are
+ errors.
+
+
+
+
+ <table class="parameters"><tr><th>Parameter</th><th>Type</th><th>Nullable</th><th>Optional</th><th>Description</th></tr><tr><td class="prmName">input</td><td class="prmType"><code><a>object</a></code></td><td class="prmNullFalse">✘</td><td class="prmOptFalse">✘</td><td class="prmDesc">The JSON-LD object to perform framing on.</td></tr><tr><td class="prmName">frame</td><td class="prmType"><code><a>object</a></code></td><td class="prmNullFalse">✘</td><td class="prmOptFalse">✘</td><td class="prmDesc">The frame to use when re-arranging the data.</td></tr><tr><td class="prmName">options</td><td class="prmType"><code><a>object</a></code></td><td class="prmNullFalse">✘</td><td class="prmOptFalse">✘</td><td class="prmDesc">A set of options that will affect the framing algorithm.</td></tr></table><table class="exceptions"><tr><th>Exception</th><th>Description</th></tr><tr><td class="excName"><a>InvalidFrame</a></td><td class="excDesc"><table class="exceptionCodes"><tr><td class="excCodeName"><code>INVALID_SYNTAX</code></td><td class="excCodeDesc">A frame must be either an object or an array of objects, if the frame
+ is neither of these types, this exception is thrown.</td></tr><tr><td class="excCodeName"><code>MULTIPLE_EMBEDS</code></td><td class="excCodeDesc">A subject IRI was specified in more than one place in the input
+ frame. More than one embed of a given subject IRI is not allowed, and if
+ requested, <em class="rfc2119" title="must">must</em> result in this exception.</td></tr></table></td></tr></table><div><em>Return type: </em><code><a>object</a></code></div></dd><dt id="widl-JsonLdProcessor-normalize-object-object-input-object-context"><code>normalize</code></dt><dd><a href="#normalization">Normalizes</a> the given <code>input</code>
+ according to the steps in the
+ <a href="#normalization-algorithm">Normalization Algorithm</a>. The
+ <code>input</code> <em class="rfc2119" title="must">must</em> be copied, normalized and returned if there are
+ no errors. If the compaction fails, <code>null</code> <em class="rfc2119" title="must">must</em> be returned.
+
+
+
+
+ <table class="parameters"><tr><th>Parameter</th><th>Type</th><th>Nullable</th><th>Optional</th><th>Description</th></tr><tr><td class="prmName">input</td><td class="prmType"><code><a>object</a></code></td><td class="prmNullFalse">✘</td><td class="prmOptFalse">✘</td><td class="prmDesc">The JSON-LD object to perform normalization upon.</td></tr><tr><td class="prmName">context</td><td class="prmType"><code><a>object</a></code></td><td class="prmNullTrue">✔</td><td class="prmOptTrue">✔</td><td class="prmDesc">An external context to use additionally to the context embedded in <code>input</code> when expanding the <code>input</code>.</td></tr></table><table class="exceptions"><tr><th>Exception</th><th>Description</th></tr><tr><td class="excName"><a>InvalidContext</a></td><td class="excDesc"><table class="exceptionCodes"><tr><td class="excCodeName"><code>INVALID_SYNTAX</code></td><td class="excCodeDesc">A general syntax error was detected in the <code>@context</code>.
+ For example, if a <code>@coerce</code> key maps to anything other than
+ a string or an array of strings, this exception would be raised.</td></tr><tr><td class="excCodeName"><code>MULTIPLE_DATATYPES</code></td><td class="excCodeDesc">There is more than one target datatype specified for a single
+ property in the list of coercion rules. This means that the processor
+ does not know what the developer intended for the target datatype for a
+ property.</td></tr></table></td></tr></table><div><em>Return type: </em><code><a>object</a></code></div></dd><dt id="widl-JsonLdProcessor-triples-object-object-input-JsonLdTripleCallback-tripleCallback-object-context"><code>triples</code></dt><dd>Processes the <code>input</code> according to the
+ <a href="#rdf-conversion-algorithm">RDF Conversion Algorithm</a>, calling
+ the provided <code>tripleCallback</code> for each triple generated.
+
+
+
+
+ <table class="parameters"><tr><th>Parameter</th><th>Type</th><th>Nullable</th><th>Optional</th><th>Description</th></tr><tr><td class="prmName">input</td><td class="prmType"><code><a>object</a></code></td><td class="prmNullFalse">✘</td><td class="prmOptFalse">✘</td><td class="prmDesc">The JSON-LD object to process when outputting triples.</td></tr><tr><td class="prmName">tripleCallback</td><td class="prmType"><code><a href="#idl-def-JsonLdTripleCallback" class="idlType"><code>JsonLdTripleCallback</code></a></code></td><td class="prmNullFalse">✘</td><td class="prmOptFalse">✘</td><td class="prmDesc">A callback that is called whenever a processing error occurs on
+ the given <code>input</code>.
+ <div class="issue">This callback should be aligned with the
+ RDF API.</div></td></tr><tr><td class="prmName">context</td><td class="prmType"><code><a>object</a></code></td><td class="prmNullTrue">✔</td><td class="prmOptTrue">✔</td><td class="prmDesc">An external context to use additionally to the context embedded in <code>input</code> when expanding the <code>input</code>.</td></tr></table><table class="exceptions"><tr><th>Exception</th><th>Description</th></tr><tr><td class="excName"><a>InvalidContext</a></td><td class="excDesc"><table class="exceptionCodes"><tr><td class="excCodeName"><code>INVALID_SYNTAX</code></td><td class="excCodeDesc">A general syntax error was detected in the <code>@context</code>.
+ For example, if a <code>@coerce</code> key maps to anything other than
+ a string or an array of strings, this exception would be raised.</td></tr><tr><td class="excCodeName"><code>MULTIPLE_DATATYPES</code></td><td class="excCodeDesc">There is more than one target datatype specified for a single
+ property in the list of coercion rules. This means that the processor
+ does not know what the developer intended for the target datatype for a
+ property.</td></tr></table></td></tr></table><div><em>Return type: </em><code><a>object</a></code></div></dd></dl></div>
+
+</div>
+
+<div id="jsonldtriplecallback" class="section">
+<h3><span class="secno">2.2 </span>JsonLdTripleCallback</h3>
+<p>The JsonLdTripleCallback is called whenever the processor generates a
+triple during the <code>triple()</code> call.</p>
+
+<pre class="idl"><span class="idlInterface" id="idl-def-JsonLdTripleCallback">[<span class="extAttr">NoInterfaceObject Callback</span>]
+interface <span class="idlInterfaceID">JsonLdTripleCallback</span> {
+<span class="idlMethod"> <span class="idlMethType"><a>void</a></span> <span class="idlMethName"><a href="#widl-JsonLdTripleCallback-triple-void-DOMString-subject-DOMString-property-DOMString-objectType-DOMString-object-DOMString-datatype-DOMString-language">triple</a></span> (<span class="idlParam"><span class="idlParamType"><a>DOMString</a></span> <span class="idlParamName">subject</span></span>, <span class="idlParam"><span class="idlParamType"><a>DOMString</a></span> <span class="idlParamName">property</span></span>, <span class="idlParam"><span class="idlParamType"><a>DOMString</a></span> <span class="idlParamName">objectType</span></span>, <span class="idlParam"><span class="idlParamType"><a>DOMString</a></span> <span class="idlParamName">object</span></span>, <span class="idlParam"><span class="idlParamType"><a>DOMString</a>?</span> <span class="idlParamName">datatype</span></span>, <span class="idlParam"><span class="idlParamType"><a>DOMString</a>?</span> <span class="idlParamName">language</span></span>);</span>
+};</span>
+</pre><div id="methods-1" class="section"><h4><span class="secno">2.2.1 </span>Methods</h4><dl class="methods"><dt id="widl-JsonLdTripleCallback-triple-void-DOMString-subject-DOMString-property-DOMString-objectType-DOMString-object-DOMString-datatype-DOMString-language"><code>triple</code></dt><dd>This callback is invoked whenever a triple is generated by the processor.
+
+ <table class="parameters"><tr><th>Parameter</th><th>Type</th><th>Nullable</th><th>Optional</th><th>Description</th></tr><tr><td class="prmName">subject</td><td class="prmType"><code><a>DOMString</a></code></td><td class="prmNullFalse">✘</td><td class="prmOptFalse">✘</td><td class="prmDesc">The subject IRI that is associated with the triple.</td></tr><tr><td class="prmName">property</td><td class="prmType"><code><a>DOMString</a></code></td><td class="prmNullFalse">✘</td><td class="prmOptFalse">✘</td><td class="prmDesc">The property IRI that is associated with the triple.</td></tr><tr><td class="prmName">objectType</td><td class="prmType"><code><a>DOMString</a></code></td><td class="prmNullFalse">✘</td><td class="prmOptFalse">✘</td><td class="prmDesc">The type of object that is associated with the triple. Valid values
+ are <code>IRI</code> and <code>literal</code>.</td></tr><tr><td class="prmName">object</td><td class="prmType"><code><a>DOMString</a></code></td><td class="prmNullFalse">✘</td><td class="prmOptFalse">✘</td><td class="prmDesc">The object value associated with the subject and the property.</td></tr><tr><td class="prmName">datatype</td><td class="prmType"><code><a>DOMString</a></code></td><td class="prmNullTrue">✔</td><td class="prmOptFalse">✘</td><td class="prmDesc">The datatype associated with the object.</td></tr><tr><td class="prmName">language</td><td class="prmType"><code><a>DOMString</a></code></td><td class="prmNullTrue">✔</td><td class="prmOptFalse">✘</td><td class="prmDesc">The language associated with the object in BCP47 format.</td></tr></table><div><em>No exceptions.</em></div><div><em>Return type: </em><code><a>void</a></code></div></dd></dl></div>
+</div>
+
+
+</div>
+
+<div id="algorithms" class="section">
+
+<!-- OddPage -->
+<h2><span class="secno">3. </span>Algorithms</h2>
+
+<p>All algorithms described in this section are intended to operate on
+language-native data structures. That is, the serialization to a text-based
+JSON document isn't required as input or output to any of these algorithms and
+language-native data structures <em class="rfc2119" title="must">must</em> be used where applicable.</p>
+
+<div id="syntax-tokens-and-keywords" class="section">
+ <h3><span class="secno">3.1 </span>Syntax Tokens and Keywords</h3>
+
+ <p>JSON-LD specifies a number of syntax tokens and keywords that are using
+ in all algorithms described in this section:</p>
+
+ <dl>
+ <dt><code>@context</code></dt><dd>Used to set the <a class="tref internalDFN" title="local_context" href="#dfn-local_context">local context</a>.</dd>
+ <dt><code>@base</code></dt><dd>Used to set the base IRI for all object IRIs affected by the <a class="tref internalDFN" title="active_context" href="#dfn-active_context">active context</a>.</dd>
+ <dt><code>@vocab</code></dt><dd>Used to set the base IRI for all property IRIs affected by the <a class="tref internalDFN" title="active_context" href="#dfn-active_context">active context</a>.</dd>
+ <dt><code>@coerce</code></dt><dd>Used to specify type coercion rules.</dd>
+ <dt><code>@literal</code></dt><dd>Used to specify a literal value.</dd>
+ <dt><code>@iri</code></dt><dd>Used to specify an IRI value.</dd>
+ <dt><code>@language</code></dt><dd>Used to specify the language for a literal.</dd>
+ <dt><code>@datatype</code></dt><dd>Used to specify the datatype for a literal.</dd>
+ <dt><code>:</code></dt><dd>The separator for JSON keys and values that use the <a class="tref" title="prefix">prefix</a> mechanism.</dd>
+ <dt><code>@subject</code></dt><dd>Sets the active subject.</dd>
+ <dt><code>@type</code></dt><dd>Used to set the type of the active subject.</dd>
+ </dl>
+</div>
+
+<div id="algorithm-terms" class="section">
+ <h3><span class="secno">3.2 </span>Algorithm Terms</h3>
+ <dl>
+ <dt><dfn title="initial_context" id="dfn-initial_context">initial context</dfn></dt>
+ <dd>
+ a context that is specified to the algorithm before processing begins.
+ </dd>
+ <dt><dfn title="active_subject" id="dfn-active_subject">active subject</dfn></dt>
+ <dd>
+ the currently active subject that the processor should use when
+ processing.
+ </dd>
+ <dt><dfn title="active_property" id="dfn-active_property">active property</dfn></dt>
+ <dd>
+ the currently active property that the processor should use when
+ processing.
+ </dd>
+ <dt><dfn title="active_object" id="dfn-active_object">active object</dfn></dt>
+ <dd>
+ the currently active object that the processor should use when
+ processing.
+ </dd>
+ <dt><dfn title="active_context" id="dfn-active_context">active context</dfn></dt>
+ <dd>
+ a context that is used to resolve <a class="tref" title="prefix">prefix</a>es and
+ <a class="tref" title="term">term</a>s while the processing
+ algorithm is running. The <a class="tref internalDFN" title="active_context" href="#dfn-active_context">active context</a> is the context
+ contained within the <a class="tref internalDFN" title="processor_state" href="#dfn-processor_state">processor state</a>.
+ </dd>
+ <dt><dfn title="local_context" id="dfn-local_context">local context</dfn></dt>
+ <dd>
+ a context that is specified within a <a class="tref internalDFN" title="JSON_object" href="#dfn-json_object">JSON object</a>,
+ specified via the <code>@context</code> keyword.
+ </dd>
+ <dt><dfn title="processor_state" id="dfn-processor_state">processor state</dfn></dt>
+ <dd>
+ the <a class="tref internalDFN" title="processor_state" href="#dfn-processor_state">processor state</a>, which includes the <a class="tref" title="active__context">active
+ context</a>, <a class="tref" title="current_subject">current subject</a>, and
+ <a class="tref" title="current_property">current property</a>. The <a class="tref internalDFN" title="processor_state" href="#dfn-processor_state">processor state</a> is managed
+ as a stack with elements from the previous <a class="tref internalDFN" title="processor_state" href="#dfn-processor_state">processor state</a>
+ copied into a new <a class="tref internalDFN" title="processor_state" href="#dfn-processor_state">processor state</a> when entering a new
+ <a class="tref internalDFN" title="JSON_object" href="#dfn-json_object">JSON object</a>.
+ </dd>
+ <dt><dfn title="JSON-LD_input" id="dfn-json-ld_input">JSON-LD input</dfn></dt>
+ <dd>
+ The JSON-LD data structure that is provided as input to the algorithm.
+ </dd>
+ <dt><dfn title="JSON-LD_output" id="dfn-json-ld_output">JSON-LD output</dfn></dt>
+ <dd>
+ The JSON-LD data structure that is produced as output by the algorithm.
+ </dd>
+
+ </dl>
+</div>
+
+<div id="context-1" class="section">
+ <h3 id="context"><span class="secno">3.3 </span>Context</h3>
+ <p>
+ Processing of JSON-LD data structure is managed recursively.
+ During processing, each rule is applied using information provided by the <a class="tref internalDFN" title="active_context" href="#dfn-active_context">active context</a>.
+ Processing begins by pushing a new <a class="tref internalDFN" title="processor_state" href="#dfn-processor_state">processor state</a> onto the <a class="tref internalDFN" title="processor_state" href="#dfn-processor_state">processor state</a> stack and
+ initializing the <a class="tref internalDFN" title="active_context" href="#dfn-active_context">active context</a> with the <a class="tref internalDFN" title="initial_context" href="#dfn-initial_context">initial context</a>. If a <a class="tref internalDFN" title="local_context" href="#dfn-local_context">local context</a> is encountered,
+ information from the <a class="tref internalDFN" title="local_context" href="#dfn-local_context">local context</a> is merged into the <a class="tref internalDFN" title="active_context" href="#dfn-active_context">active context</a>.
+ </p>
+ <p>
+ The <a class="tref internalDFN" title="active_context" href="#dfn-active_context">active context</a> is used for expanding keys and values of a <a class="tref internalDFN" title="JSON_object" href="#dfn-json_object">JSON object</a> (or elements
+ of a list (see <span a="#list-processing">List Processing</span>)).
+ </p>
+ <p>
+ A <a class="tref internalDFN" title="local_context" href="#dfn-local_context">local context</a> is identified within a <a class="tref internalDFN" title="JSON_object" href="#dfn-json_object">JSON object</a> having a key of
+ <code>@context</code> with <a class="tref internalDFN" title="string" href="#dfn-string">string</a> or a <a class="tref internalDFN" title="JSON_object" href="#dfn-json_object">JSON object</a> value. When processing a <a class="tref" title="local__context">local
+ context</a>, special processing rules apply:
+ </p>
+ <ol class="algorithm">
+ <li>Create a new, empty <a class="tref internalDFN" title="local_context" href="#dfn-local_context">local context</a>.</li>
+ <li>
+ If the value is a simple <a class="tref internalDFN" title="string" href="#dfn-string">string</a>, it <em class="rfc2119" title="must">must</em> have a lexical form of IRI and used to initialize
+ a new JSON document which replaces the value for subsequent processing.
+ </li>
+ <li>If the value is a <a class="tref internalDFN" title="JSON_object" href="#dfn-json_object">JSON object</a>, perform the following steps:
+ <ol class="algorithm">
+ <li>
+ If the <a class="tref internalDFN" title="JSON_object" href="#dfn-json_object">JSON object</a> has a <code>@base</code> key, it <em class="rfc2119" title="must">must</em> have a value of a simple
+ <a class="tref internalDFN" title="string" href="#dfn-string">string</a> with the lexical form of an absolute IRI. Add the base mapping to the <a class="tref" title="local__context">local
+ context</a>. <p class="issue">Turtle allows @base to be relative. If we did this, we
+ would have to add <a href="#iri-expansion">IRI Expansion</a>.</p>
+ </li>
+ <li>
+ If the <a class="tref internalDFN" title="JSON_object" href="#dfn-json_object">JSON object</a> has a <code>@vocab</code> key, it <em class="rfc2119" title="must">must</em> have a value of a simple
+ <a class="tref internalDFN" title="string" href="#dfn-string">string</a> with the lexical form of an absolute IRI. Add the vocabulary mapping to the
+ <a class="tref internalDFN" title="local_context" href="#dfn-local_context">local context</a> after performing <a href="#iri-expansion">IRI Expansion</a> on
+ the associated value.
+ </li>
+ <li>
+ If the <a class="tref internalDFN" title="JSON_object" href="#dfn-json_object">JSON object</a> has a <code>@coerce</code> key, it <em class="rfc2119" title="must">must</em> have a value of a
+ <a class="tref internalDFN" title="JSON_object" href="#dfn-json_object">JSON object</a>. Add the <code>@coerce</code> mapping to the <a class="tref internalDFN" title="local_context" href="#dfn-local_context">local context</a>
+ performing <a href="#iri-expansion">IRI Expansion</a> on the associated value(s).
+ </li>
+ <li>
+ Otherwise, the key <em class="rfc2119" title="must">must</em> have the lexical form of <cite><a href="http://www.w3.org/TR/2009/REC-xml-names-20091208/#NT-NCName">NCName</a></cite> and
+ <em class="rfc2119" title="must">must</em> have the value of a simple <a class="tref internalDFN" title="string" href="#dfn-string">string</a> with the lexical form of IRI. Merge the key-value
+ pair into the <a class="tref internalDFN" title="local_context" href="#dfn-local_context">local context</a>.
+ </li>
+ </ol>
+ </li>
+ <li>
+ Merge the of <a class="tref internalDFN" title="local_context" href="#dfn-local_context">local context</a>'s <code>@coerce</code> mapping into the
+ <a class="tref internalDFN" title="active_context" href="#dfn-active_context">active context</a>'s <code>@coerce</code> mapping as described <a href="#coerce">below</a>.
+ </li>
+ <li>
+ Merge all entries other than the <code>@coerce</code> mapping from the <a class="tref internalDFN" title="local_context" href="#dfn-local_context">local context</a> to the
+ <a class="tref internalDFN" title="active_context" href="#dfn-active_context">active context</a> overwriting any duplicate values.
+ </li>
+ </ol>
+
+ <div id="coerce" class="section">
+ <h4><span class="secno">3.3.1 </span>Coerce</h4>
+ <p>
+ Map each key-value pair in the <a class="tref internalDFN" title="local_context" href="#dfn-local_context">local context</a>'s
+ <code>@coerce</code> mapping into the <a class="tref internalDFN" title="active_context" href="#dfn-active_context">active context</a>'s
+ <code>@coerce</code> mapping, overwriting any duplicate values in
+ the <a class="tref internalDFN" title="active_context" href="#dfn-active_context">active context</a>'s <code>@coerce</code> mapping.
+ The <code>@coerce</code> mapping has either a single
+ <code>prefix:term</code> value, a single <a class="tref" title="term">term</a> value or an
+ <a class="tref internalDFN" title="array" href="#dfn-array">array</a> of <code>prefix:term</code> or <a class="tref" title="term">term</a> values.
+ When merging with an existing mapping in the <a class="tref internalDFN" title="active_context" href="#dfn-active_context">active context</a>,
+ map all <a class="tref" title="prefix">prefix</a> and <a class="tref" title="term">term</a> values to
+ <a class="tref internalDFN" title="array" href="#dfn-array">array</a> form and replace with the union of the value from
+ the <a class="tref internalDFN" title="local_context" href="#dfn-local_context">local context</a> and the value of the
+ <a class="tref internalDFN" title="active_context" href="#dfn-active_context">active context</a>. If the result is an <a class="tref internalDFN" title="array" href="#dfn-array">array</a>
+ with a single value, the processor <em class="rfc2119" title="may">may</em> represent this as a string value.
+ </p>
+ </div>
+
+ <div id="initial-context" class="section">
+ <h4><span class="secno">3.3.2 </span>Initial Context</h4>
+ <p>The <a class="tref internalDFN" title="initial_context" href="#dfn-initial_context">initial context</a> is initialized as follows:</p>
+ <ul>
+ <li>
+ <code>@base</code> is set using <cite><href="http: www.ietf.org="" rfc="" rfc2396.txt"="">section 5.1 Establishing a
+ Base URI</href="http:></cite> of [<cite><a class="bibref" rel="biblioentry" href="#bib-RFC3986">RFC3986</a></cite>]. Processors <em class="rfc2119" title="may">may</em> provide a means
+ of setting the base IRI programatically.
+ </li>
+ <li><code>@coerce</code> is set with a single mapping from <code>@iri</code> to <code>@type</code>.</li>
+ </ul>
+ <pre class="example">{
+ "@base": <span class="diff">document-location</span>,
+ "@coerce": {
+ "@iri": "@type"
+ }
+}</pre>
+ </div>
+</div>
+
+<div id="iri-expansion" class="section">
+ <h3><span class="secno">3.4 </span>IRI Expansion</h3>
+ <p>Keys and some values are evaluated to produce an IRI. This section defines an algorithm for
+ transforming a value representing an IRI into an actual IRI.</p>
+ <p>IRIs may be represented as an absolute IRI, a <a class="tref" title="term">term</a>, a <a class="tref" title="prefix">prefix</a>:<a class="tref" title="term">term</a> construct, or as a value relative to <code>@base</code>
+ or <code>@vocab</code>.</p>
+ <p>The algorithm for generating an IRI is:
+ </p><ol class="algorithm">
+ <li>Split the value into a <em>prefix</em> and <em>suffix</em> from the first occurrence of ':'.</li>
+ <li>If the prefix is a '_' (underscore), the IRI is unchanged.</li>
+ <li>If the <a class="tref internalDFN" title="active_context" href="#dfn-active_context">active context</a> contains a mapping for <em>prefix</em>, generate an IRI
+ by prepending the mapped prefix to the (possibly empty) suffix using textual concatenation. Note that an empty
+ suffix and no suffix (meaning the value contains no ':' string at all) are treated equivalently.</li>
+ <li>If the IRI being processed is for a property (i.e., a key's value in a <a class="tref internalDFN" title="JSON_object" href="#dfn-json_object">JSON object</a>, or a
+ value in a <code>@coerce</code> mapping) and the active context has a <code>@vocab</code> mapping,
+ join the mapped value to the suffix using textual concatenation.</li>
+ <li>If the IRI being processed is for a subject or object (i.e., not a property) and the active context has a <code>@base</code> mapping,
+ join the mapped value to the suffix using the method described in [<cite><a class="bibref" rel="biblioentry" href="#bib-RFC3986">RFC3986</a></cite>].</li>
+ <li>Otherwise, use the value directly as an IRI.</li>
+ </ol>
+ <p></p>
+</div>
+
+<div id="iri-compaction" class="section">
+ <h3><span class="secno">3.5 </span>IRI Compaction</h3>
+ <p>Some keys and values are expressed using IRIs. This section defines an
+ algorithm for transforming an IRI to a compact IRI using the
+ <a class="tref" title="term">term</a>s and <a class="tref" title="prefix">prefix</a>es specified in the
+ <a class="tref internalDFN" title="local_context" href="#dfn-local_context">local context</a>.</p>
+
+ <p>The algorithm for generating a compacted IRI is:
+ </p><ol class="algorithm">
+ <li>Search every key-value pair in the <a class="tref internalDFN" title="active_context" href="#dfn-active_context">active context</a> for
+ a <a class="tref" title="term">term</a> that is a complete match
+ against the IRI. If a complete match is found, the resulting compacted
+ IRI is the <a class="tref" title="term">term</a> associated with the IRI in the
+ <a class="tref internalDFN" title="active_context" href="#dfn-active_context">active context</a>.</li>
+ <li>If a complete match is not found, search for a partial match from
+ the beginning of the IRI. For all matches that are found, the resulting
+ compacted IRI is the <a class="tref" title="prefix">prefix</a> associated with the partially
+ matched IRI in the <a class="tref internalDFN" title="active_context" href="#dfn-active_context">active context</a> concatenated with a
+ colon (:) character and the unmatched part of the string. If there is
+ more than one compacted IRI produced, the final value is the
+ shortest and lexicographically least value of the entire set of compacted IRIs.</li>
+ </ol>
+ <p></p>
+</div>
+
+<div id="value-expansion" class="section">
+ <h3><span class="secno">3.6 </span>Value Expansion</h3>
+ <p>Some values in JSON-LD can be expressed in a compact form. These values
+ are required to be expanded at times when processing JSON-LD documents.
+ </p>
+
+ <p>The algorithm for expanding a value is:
+ </p><ol class="algorithm">
+ <li>If the key that is associated with the value has an associated
+ coercion entry in the <a class="tref internalDFN" title="local_context" href="#dfn-local_context">local context</a>, the resulting
+ expansion is an object populated according to the following steps:
+ <ol class="algorithm">
+ <li>If the coercion target is <code>@iri</code>, expand the value
+ by adding a new key-value pair where the key is <code>@iri</code>
+ and the value is the expanded IRI according to the
+ <a href="#iri-expansion">IRI Expansion</a> rules.</li>
+ <li>If the coercion target is a typed literal, expand the value
+ by adding two new key-value pairs. The first key-value pair
+ will be <code>@literal</code> and the unexpanded value. The second
+ key-value pair will be <code>@datatype</code> and the associated
+ coercion datatype expanded according to the
+ <a href="#iri-expansion">IRI Expansion</a> rules.</li>
+ </ol>
+ </li>
+ </ol>
+ <p></p>
+</div>
+
+<div id="value-compaction" class="section">
+ <h3><span class="secno">3.7 </span>Value Compaction</h3>
+ <p>Some values, such as IRIs and typed literals, may be expressed in an
+ expanded form in JSON-LD. These values are required to be compacted at
+ times when processing JSON-LD documents.
+ </p>
+
+ <p>The algorithm for compacting a value is:
+ </p><ol class="algorithm">
+ <li>If the <a class="tref internalDFN" title="local_context" href="#dfn-local_context">local context</a> contains a coercion target for the
+ key that is associated with the value, compact the value using the
+ following steps:
+ <ol class="algorithm">
+ <li>If the coercion target is an <code>@iri</code>, the compacted
+ value is the value associated with the <code>@iri</code> key,
+ processed according to the
+ <a href="#iri-compaction">IRI Compaction</a> steps.</li>
+ <li>If the coercion target is a typed literal, the compacted
+ value is the value associated with the <code>@literal</code> key.
+ </li>
+ <li>Otherwise, the value is not modified.</li>
+ </ol>
+ </li>
+ </ol>
+ <p></p>
+</div>
+
+<div id="expansion" class="section">
+<h3><span class="secno">3.8 </span>Expansion</h3>
+
+<p class="issue">This algorithm is a work in progress, do not implement it.</p>
+
+<p>As stated previously, expansion is the process of taking a JSON-LD
+input and expanding all IRIs and typed literals to their fully-expanded form.
+The output will not contain a single context declaration and will have all IRIs
+and typed literals fully expanded.
+</p>
+
+<div id="expansion-algorithm" class="section">
+<h4><span class="secno">3.8.1 </span>Expansion Algorithm</h4>
+
+<ol class="algorithm">
+ <li>If the top-level item in the <a class="tref internalDFN" title="JSON-LD_input" href="#dfn-json-ld_input">JSON-LD input</a> is an <a class="tref internalDFN" title="array" href="#dfn-array">array</a>,
+ process each item in the <a class="tref internalDFN" title="array" href="#dfn-array">array</a> recursively using this algorithm.</li>
+ <li>If the top-level item in the <a class="tref internalDFN" title="JSON-LD_input" href="#dfn-json-ld_input">JSON-LD input</a> is an object,
+ update the <a class="tref internalDFN" title="local_context" href="#dfn-local_context">local context</a> according to the steps outlined in
+ the <a href="#context">context</a> section. Process each key, expanding
+ the key according to the <a href="#iri-expansion">IRI Expansion</a> rules.</li>
+ <ol class="algorithm">
+ <li>Process each value associated with each key:
+ <ol class="algorithm">
+ <li>If the value is an <a class="tref internalDFN" title="array" href="#dfn-array">array</a>, process each item in the <a class="tref internalDFN" title="array" href="#dfn-array">array</a>
+ recursively using this algorithm.</li>
+ <li>If the value is an object, process the object recursively
+ using this algorithm.</li>
+ <li>Otherwise, check to see the associated key has an associated
+ coercion rule. If the value should be coerced, expand the value
+ according to the <a href="#value-expansion">Value Expansion</a> rules.
+ If the value does not need to be coerced, leave the value as-is.
+ </li>
+ </ol>
+ </li><li>Remove the context from the object.</li>
+ </ol>
+</ol>
+</div>
+
+</div>
+
+<div id="compaction" class="section">
+<h3><span class="secno">3.9 </span>Compaction</h3>
+
+<p class="issue">This algorithm is a work in progress, do not implement it.</p>
+
+<p>As stated previously, compaction is the process of taking a JSON-LD
+input and compacting all IRIs using a given context. The output
+will contain a single top-level context declaration and will only use
+<a class="tref" title="term">term</a>s and <a class="tref" title="prefix">prefix</a>es and will ensure that all
+typed literals are fully compacted.
+</p>
+
+<div id="compaction-algorithm" class="section">
+<h4><span class="secno">3.9.1 </span>Compaction Algorithm</h4>
+
+<ol class="algorithm">
+ <li>Perform the <a href="#expansion-algorithm">Expansion Algorithm</a> on
+ the <a class="tref internalDFN" title="JSON-LD_input" href="#dfn-json-ld_input">JSON-LD input</a>. This removes any existing context to allow the given context to be cleanly applied.</li>
+ <li>Set the <a class="tref internalDFN" title="active_context" href="#dfn-active_context">active context</a> to the given context.
+ </li><li>If the top-level item is an <a class="tref internalDFN" title="array" href="#dfn-array">array</a>, process each item in the <a class="tref internalDFN" title="array" href="#dfn-array">array</a>
+ recursively, starting at this step.
+ </li><li>If the top-level item is an object, compress each key using the steps
+ defined in <a href="#iri-compaction">IRI Compaction</a> and compress each
+ value using the steps defined in
+ <a href="#value-compaction">Value Compaction</a>.</li>
+
+</ol>
+</div>
+
+</div>
+
+
+<div id="framing" class="section">
+<h3><span class="secno">3.10 </span>Framing</h3>
+
+<p class="issue">This algorithm is a work in progress, do not implement it.</p>
+
+<p>A JSON-LD document is a representation of a directed graph. A single
+directed graph can have many different serializations, each expressing
+exactly the same information. Developers typically don't work directly with
+graphs, but rather, prefer trees when dealing with JSON. While mapping a graph
+to a tree can be done, the layout of the end result must be specified in
+advance. This section defines an algorithm for mapping a graph to
+a tree given a <a class="tref" title="frame">frame</a>.
+</p>
+
+<div id="framing-algorithm-terms" class="section">
+<h4><span class="secno">3.10.1 </span>Framing Algorithm Terms</h4>
+ <dl>
+ <dt><dfn title="input_frame" id="dfn-input_frame">input frame</dfn></dt>
+ <dd>
+ the initial <a class="tref" title="frame">frame</a> provided to the framing algorithm.
+ </dd>
+ <dt><dfn title="framing_context" id="dfn-framing_context">framing context</dfn></dt>
+ <dd>
+ a context containing the <a class="tref internalDFN" title="object_embed_flag" href="#dfn-object_embed_flag">object embed flag</a>, the
+ <a class="tref internalDFN" title="explicit_inclusion_flag" href="#dfn-explicit_inclusion_flag">explicit inclusion flag</a> and the
+ <a class="tref" title="omit_default_flag">omit default flag</a>.
+ </dd>
+ <dt><dfn title="object_embed_flag" id="dfn-object_embed_flag">object embed flag</dfn></dt>
+ <dd>
+ a flag specifying that objects should be directly embedded in the output,
+ instead of being referred to by their IRI.
+ </dd>
+ <dt><dfn title="explicit_inclusion_flag" id="dfn-explicit_inclusion_flag">explicit inclusion flag</dfn></dt>
+ <dd>
+ a flag specifying that for properties to be included in the output, they
+ must be explicitly declared in the <a class="tref internalDFN" title="framing_context" href="#dfn-framing_context">framing context</a>.
+ </dd>
+ <dt><dfn title="omit_missing_properties_flag" id="dfn-omit_missing_properties_flag">omit missing properties flag</dfn></dt>
+ <dd>
+ a flag specifying that properties that are missing from the
+ <a class="tref internalDFN" title="JSON-LD_input" href="#dfn-json-ld_input">JSON-LD input</a> should be omitted from the output.
+ </dd>
+ <dt><dfn title="match_limit" id="dfn-match_limit">match limit</dfn></dt>
+ <dd>
+ A value specifying the maximum number of matches to accept when building
+ arrays of values during the framing algorithm. A value of -1 specifies
+ that there is no match limit.
+ </dd>
+ <dt><dfn title="map_of_embedded_subjects" id="dfn-map_of_embedded_subjects">map of embedded subjects</dfn></dt>
+ <dd>
+ A map that tracks if a subject has been embedded in the output of the
+ <a href="#framing-algorithm">Framing Algorithm</a>.
+ </dd>
+ </dl>
+</div>
+
+<div id="framing-algorithm" class="section">
+<h4><span class="secno">3.10.2 </span>Framing Algorithm</h4>
+
+<p>The framing algorithm takes <a class="tref internalDFN" title="JSON-LD_input" href="#dfn-json-ld_input">JSON-LD input</a> that has been
+normalized according to the
+<a href="#normalization-algorithm">Normalization Algorithm</a>
+(<strong>normalized input</strong>), an
+<a class="tref internalDFN" title="input_frame" href="#dfn-input_frame">input frame</a> that has been expanded according to the
+<a href="#expansion-algorithm">Expansion Algorithm</a>
+(<strong>expanded frame</strong>), and a number of options and produces
+<a class="tref internalDFN" title="JSON-LD_output" href="#dfn-json-ld_output">JSON-LD output</a>. The following series of steps is the recursive
+portion of the framing algorithm:
+</p>
+
+<ol class="algorithm">
+ <li>Initialize the <a class="tref internalDFN" title="framing_context" href="#dfn-framing_context">framing context</a> by setting the
+ <a class="tref internalDFN" title="object_embed_flag" href="#dfn-object_embed_flag">object embed flag</a>, clearing the
+ <a class="tref internalDFN" title="explicit_inclusion_flag" href="#dfn-explicit_inclusion_flag">explicit inclusion flag</a>, and clearing the
+ <a class="tref internalDFN" title="omit_missing_properties_flag" href="#dfn-omit_missing_properties_flag">omit missing properties flag</a>. Override these values
+ based on input options provided to the algorithm by the application.
+ </li>
+ <li>Generate a <dfn title="list_of_frames" id="dfn-list_of_frames">list of frames</dfn> by processing the
+ <strong>expanded frame</strong>:
+ <ol class="algorithm">
+ <li>If the <strong>expanded frame</strong> is not an <a class="tref internalDFN" title="array" href="#dfn-array">array</a>, set
+ <a class="tref internalDFN" title="match_limit" href="#dfn-match_limit">match limit</a> to 1, place the
+ <strong>expanded frame</strong> into the <a class="tref internalDFN" title="list_of_frames" href="#dfn-list_of_frames">list of frames</a>,
+ and set the <a class="tref internalDFN" title="JSON-LD_output" href="#dfn-json-ld_output">JSON-LD output</a> to <code>null</code>.</li>
+ <li>If the <strong>expanded frame</strong> is an empty <a class="tref internalDFN" title="array" href="#dfn-array">array</a>, place an
+ empty object into the <a class="tref internalDFN" title="list_of_frames" href="#dfn-list_of_frames">list of frames</a>,
+ set the <a class="tref internalDFN" title="JSON-LD_output" href="#dfn-json-ld_output">JSON-LD output</a> to an <a class="tref internalDFN" title="array" href="#dfn-array">array</a>, and set
+ <a class="tref internalDFN" title="match_limit" href="#dfn-match_limit">match limit</a> to -1.</li>
+ <li>If the <strong>expanded frame</strong> is a non-empty <a class="tref internalDFN" title="array" href="#dfn-array">array</a>, add
+ each item in the <strong>expanded frame</strong> into the
+ <a class="tref internalDFN" title="list_of_frames" href="#dfn-list_of_frames">list of frames</a>, set the <a class="tref internalDFN" title="JSON-LD_output" href="#dfn-json-ld_output">JSON-LD output</a> to an
+ <a class="tref internalDFN" title="array" href="#dfn-array">array</a>, and set <a class="tref internalDFN" title="match_limit" href="#dfn-match_limit">match limit</a> to -1.</li>
+ </ol></li>
+ <li>Create a <dfn title="match_array" id="dfn-match_array">match array</dfn> for each <strong>expanded frame</strong>
+ in the <a class="tref internalDFN" title="list_of_frames" href="#dfn-list_of_frames">list of frames</a> halting when either the
+ <a class="tref internalDFN" title="match_limit" href="#dfn-match_limit">match limit</a> is zero or the end of the
+ <a class="tref internalDFN" title="list_of_frames" href="#dfn-list_of_frames">list of frames</a> is reached. If an
+ <strong>expanded frame</strong> is
+ not an object, the processor <em class="rfc2119" title="must">must</em> throw a <code>Invalid Frame Format</code>
+ exception. Add each matching item from the <strong>normalized input</strong>
+ to the <a class="tref" title="matches_array">matches array</a> and decrement the
+ <a class="tref internalDFN" title="match_limit" href="#dfn-match_limit">match limit</a> by 1 if:
+ <ol class="algorithm">
+ <li>The <strong>expanded frame</strong> has an <code>rdf:type</code>
+ that exists in the item's list of <code>rdf:type</code>s. Note:
+ the <code>rdf:type</code> can be an <a class="tref internalDFN" title="array" href="#dfn-array">array</a>, but only one value needs
+ to be in common between the item and the
+ <strong>expanded frame</strong> for a match.</li>
+ <li>The <strong>expanded frame</strong> does not have an
+ <code>rdf:type</code> property, but every property in the
+ <strong>expanded frame</strong> exists in the item.</li>
+ </ol></li>
+ <li>Process each item in the <a class="tref internalDFN" title="match_array" href="#dfn-match_array">match array</a> with its associated
+ <dfn title="match_frame" id="dfn-match_frame">match frame</dfn>:
+ <ol class="algorithm">
+ <li>If the <a class="tref internalDFN" title="match_frame" href="#dfn-match_frame">match frame</a> contains an <code>@embed</code>
+ keyword, set the <a class="tref internalDFN" title="object_embed_flag" href="#dfn-object_embed_flag">object embed flag</a> to its value.
+ If the <a class="tref internalDFN" title="match_frame" href="#dfn-match_frame">match frame</a> contains an <code>@explicit</code>
+ keyword, set the <a class="tref internalDFN" title="explicit_inclusion_flag" href="#dfn-explicit_inclusion_flag">explicit inclusion flag</a> to its value.
+ Note: if the keyword exists, but the value is neither
+ <code>true</code> or <code>false</code>, set the associated flag to
+ <code>true</code>.</li>
+ <li>If the <a class="tref internalDFN" title="object_embed_flag" href="#dfn-object_embed_flag">object embed flag</a> is cleared and the item has
+ the <code>@subject</code> property, replace the item with the value
+ of the <code>@subject</code> property.</li>
+ <li>If the <a class="tref internalDFN" title="object_embed_flag" href="#dfn-object_embed_flag">object embed flag</a> is set and the item has
+ the <code>@subject</code> property, and its IRI is in the
+ <a class="tref internalDFN" title="map_of_embedded_subjects" href="#dfn-map_of_embedded_subjects">map of embedded subjects</a>, throw a
+ <code>Duplicate Embed</code> exception.</li>
+ <li>If the <a class="tref internalDFN" title="object_embed_flag" href="#dfn-object_embed_flag">object embed flag</a> is set and the item has
+ the <code>@subject</code> property and its IRI is not in the
+ <a class="tref internalDFN" title="map_of_embedded_subjects" href="#dfn-map_of_embedded_subjects">map of embedded subjects</a>:
+ <ol class="algorithm">
+ <li>If the <a class="tref internalDFN" title="explicit_inclusion_flag" href="#dfn-explicit_inclusion_flag">explicit inclusion flag</a> is set,
+ then delete any key from the item that does not exist in the
+ <a class="tref internalDFN" title="match_frame" href="#dfn-match_frame">match frame</a>, except <code>@subject</code>.</li>
+ <li>For each key in the <a class="tref internalDFN" title="match_frame" href="#dfn-match_frame">match frame</a>, except for
+ keywords and <code>rdf:type</code>:
+ <ol class="algorithm">
+ <li>If the key is in the item, then build a new
+ <dfn title="recursion_input_list" id="dfn-recursion_input_list">recursion input list</dfn> using the object or objects
+ associated with the key. If any object contains an
+ <code>@iri</code> value that exists in the
+ <a class="tref" title="normalized_input">normalized input</a>, replace the object in the
+ <a class="tref" title="recusion_input_list">recusion input list</a> with a new object containing
+ the <code>@subject</code> key where the value is the value of
+ the <code>@iri</code>, and all of the other key-value pairs for
+ that subject. Set the <dfn title="recursion_match_frame" id="dfn-recursion_match_frame">recursion match frame</dfn> to the
+ value associated with the <a class="tref internalDFN" title="match_frame" href="#dfn-match_frame">match frame</a>'s key. Replace
+ the value associated with the key by recursively calling this
+ algorithm using <a class="tref internalDFN" title="recursion_input_list" href="#dfn-recursion_input_list">recursion input list</a>,
+ <a class="tref internalDFN" title="recursion_match_frame" href="#dfn-recursion_match_frame">recursion match frame</a> as input.</li>
+ <li>If the key is not in the item, add the key to the item and
+ set the associated value to an empty array if the
+ <a class="tref internalDFN" title="match_frame" href="#dfn-match_frame">match frame</a> key's value is an array
+ or <code>null</code> otherwise.</li>
+ <li>If value associated with the item's key is <code>null</code>,
+ process the <a class="tref internalDFN" title="omit_missing_properties_flag" href="#dfn-omit_missing_properties_flag">omit missing properties flag</a>:
+ <ol class="algorithm">
+ <li>If the value associated with the key in the
+ <a class="tref internalDFN" title="match_frame" href="#dfn-match_frame">match frame</a> is an array, use the first frame
+ from the array as the <dfn title="property_frame" id="dfn-property_frame">property frame</dfn>, otherwise
+ set the <a class="tref internalDFN" title="property_frame" href="#dfn-property_frame">property frame</a> to an empty object.</li>
+ <li>If the <a class="tref internalDFN" title="property_frame" href="#dfn-property_frame">property frame</a> contains an
+ <code>@omitDefault</code> keyword, set the
+ <a class="tref internalDFN" title="omit_missing_properties_flag" href="#dfn-omit_missing_properties_flag">omit missing properties flag</a> to its value.
+ Note: if the keyword exists, but the value is neither
+ <code>true</code> or <code>false</code>, set the associated
+ flag to <code>true</code>.</li>
+ <li>If the <a class="tref internalDFN" title="omit_missing_properties_flag" href="#dfn-omit_missing_properties_flag">omit missing properties flag</a> is set,
+ delete the key in the item. Otherwise, if the
+ <code>@default</code> keyword is set in the
+ <a class="tref internalDFN" title="property_frame" href="#dfn-property_frame">property frame</a> set the item's value to the value
+ of <code>@default</code>.</li>
+ </ol></li>
+ </ol></li>
+ </ol>
+ </li><li>If the <a class="tref internalDFN" title="JSON-LD_output" href="#dfn-json-ld_output">JSON-LD output</a> is <code>null</code> set it to
+ the item, otherwise, append the item to the
+ <a class="tref internalDFN" title="JSON-LD_output" href="#dfn-json-ld_output">JSON-LD output</a>.
+ </li></ol>
+ </li><li>Return the <a class="tref internalDFN" title="JSON-LD_output" href="#dfn-json-ld_output">JSON-LD output</a>.</li>
+</ol>
+
+The final, non-recursive step of the framing algorithm requires the
+<a class="tref internalDFN" title="JSON-LD_output" href="#dfn-json-ld_output">JSON-LD output</a> to be compacted according to the
+<a href="#compaction-algorithm">Compaction Algorithm</a> by using the
+context provided in the <a class="tref internalDFN" title="input_frame" href="#dfn-input_frame">input frame</a>. The resulting value is the
+final output of the compaction algorithm and is what should be returned to the
+application.
+
+</div>
+
+</div>
+
+<div id="normalization" class="section">
+<h3><span class="secno">3.11 </span>Normalization</h3>
+
+<p class="issue">This algorithm is a work in progress, do not implement it.</p>
+
+<p>Normalization is the process of taking <a class="tref internalDFN" title="JSON-LD_input" href="#dfn-json-ld_input">JSON-LD input</a> and
+performing a deterministic transformation on that input that results in all
+aspects of the graph being fully expanded and named in the
+<a class="tref internalDFN" title="JSON-LD_output" href="#dfn-json-ld_output">JSON-LD output</a>. The normalized output is generated in such a way
+that any conforming JSON-LD processor will generate identical output
+given the same input. The problem is a fairly difficult technical
+problem to solve because it requires a directed graph to be ordered into a
+set of nodes and edges in a deterministic way. This is easy to do when all of
+the nodes have unique names, but very difficult to do when some of the nodes
+are not labeled.
+</p>
+
+<p>In time, there may be more than one normalization algorithm that will need
+to be identified. For identification purposes, this algorithm is named
+"Universal Graph Normalization Algorithm 2011"
+(<abbr title="Universal Graph Normalization Algorithm 2011">UGNA2011</abbr>).
+</p>
+
+<div id="normalization-algorithm-terms" class="section">
+<h4><span class="secno">3.11.1 </span>Normalization Algorithm Terms</h4>
+ <dl>
+ <dt><dfn title="label" id="dfn-label">label</dfn></dt>
+ <dd>
+ The subject IRI associated with a graph node. The subject IRI is expressed
+ using a key-value pair in a <a class="tref internalDFN" title="JSON_object" href="#dfn-json_object">JSON object</a> where the key is
+ <code>@subject</code> and the value is a string that is an IRI or
+ a <a class="tref internalDFN" title="JSON_object" href="#dfn-json_object">JSON object</a> containing the key <code>@iri</code> and
+ a value that is a string that is an IRI.
+ </dd>
+ <dt><dfn title="list_of_expanded_nodes" id="dfn-list_of_expanded_nodes">list of expanded nodes</dfn></dt>
+ <dd>
+ A list of all nodes in the <a class="tref internalDFN" title="JSON-LD_input" href="#dfn-json-ld_input">JSON-LD input</a> graph containing no
+ embedded objects and having all keys and values expanded according to the
+ steps in the <a href="#expansion-algorithm">Expansion Algorithm</a>.
+ </dd>
+ <dt><dfn title="alpha" id="dfn-alpha">alpha</dfn> and <dfn title="beta" id="dfn-beta">beta</dfn> values</dt>
+ <dd>
+ The words <a class="tref internalDFN" title="alpha" href="#dfn-alpha">alpha</a> and <a class="tref internalDFN" title="beta" href="#dfn-beta">beta</a> refer to the first and
+ second nodes or values being examined in an algorithm. The names are
+ merely used to refer to each input value to a comparison algorithm.
+ </dd>
+ <dt><dfn title="renaming_counter" id="dfn-renaming_counter">renaming counter</dfn></dt>
+ <dd>
+ A counter that is used during the
+ <a href="#node-relabeling-algorithm">Node Relabeling Algorithm</a>. The
+ counter typically starts at one (1) and counts up for every node that is
+ relabeled. There will be two such renaming counters in an implementation
+ of the normalization algorithm. The first is the
+ <a class="tref internalDFN" title="labeling_counter" href="#dfn-labeling_counter">labeling counter</a> and the second is the
+ <a class="tref" title="deterministic_labeling_counter">deterministic labeling counter</a>.
+ </dd>
+ <dt><dfn title="serialization_label" id="dfn-serialization_label">serialization label</dfn></dt>
+ <dd>
+ An identifier that is created to aid in the normalization process in the
+ <a href="#deep-comparison-algorithm">Deep Comparison Algorithm</a>. The
+ value typically takes the form of <code>s<NUMBER></code> or
+ <code>c<NUMBER></code>.
+ </dd>
+</dl>
+</div>
+
+<div id="normalization-state" class="section">
+<h4><span class="secno">3.11.2 </span>Normalization State</h4>
+
+<p>When performing the steps required by the normalization algorithm,
+it is helpful to track the many pieces of information in a
+data structure called the <dfn title="normalization_state" id="dfn-normalization_state">normalization state</dfn>. Many of these
+pieces simply provide indexes into the graph. The information
+contained in the <a class="tref internalDFN" title="normalization_state" href="#dfn-normalization_state">normalization state</a> is described below.</p>
+
+<dl>
+ <dt><dfn title="node_state" id="dfn-node_state">node state</dfn></dt>
+ <dd>
+ Each node in the graph will be assigned a <a class="tref internalDFN" title="node_state" href="#dfn-node_state">node state</a>. This
+ state contains the information necessary to deterministically
+ <a class="tref internalDFN" title="label" href="#dfn-label">label</a> all nodes in the graph. A <a class="tref internalDFN" title="node_state" href="#dfn-node_state">node state</a>
+ includes:
+ <dl>
+ <dt><dfn title="node_reference" id="dfn-node_reference">node reference</dfn></dt>
+ <dd>
+ A <a class="tref internalDFN" title="node_reference" href="#dfn-node_reference">node reference</a> is a reference to a node in the graph.
+ For a given <a class="tref internalDFN" title="node_state" href="#dfn-node_state">node state</a>, its <a class="tref internalDFN" title="node_reference" href="#dfn-node_reference">node reference</a>
+ refers to the node that the state is for. When a
+ <a class="tref internalDFN" title="node_state" href="#dfn-node_state">node state</a> is created, its <a class="tref internalDFN" title="node_reference" href="#dfn-node_reference">node reference</a>
+ should be to the node it is created for.
+ </dd>
+ <dt><dfn title="outgoing_list" id="dfn-outgoing_list">outgoing list</dfn></dt>
+ <dd>
+ Lists the <a class="tref internalDFN" title="label" href="#dfn-label">label</a>s for all nodes that are properties of
+ the <a class="tref internalDFN" title="node_reference" href="#dfn-node_reference">node reference</a>. This list should be initialized
+ by iterating over every object associated with a property in the
+ <a class="tref internalDFN" title="node_reference" href="#dfn-node_reference">node reference</a> adding its label if it is another node.
+ </dd>
+ <dt><dfn title="incoming_list" id="dfn-incoming_list">incoming list</dfn></dt>
+ <dd>
+ Lists the <a class="tref internalDFN" title="label" href="#dfn-label">label</a>s for all nodes in the graph for which
+ the <a class="tref internalDFN" title="node_reference" href="#dfn-node_reference">node reference</a> is a property. This list is
+ initialized to an empty list.
+ </dd>
+ <dt><dfn title="outgoing_serialization_map" id="dfn-outgoing_serialization_map">outgoing serialization map</dfn></dt>
+ <dd>
+ Maps node <a class="tref internalDFN" title="label" href="#dfn-label">label</a>s to <a class="tref internalDFN" title="serialization_label" href="#dfn-serialization_label-1">serialization label</a>s.
+ This map is initialized to an empty map. When this map is populated,
+ it will be filled with keys that are the <a class="tref internalDFN" title="label" href="#dfn-label">label</a>s of every node in the
+ graph with a label that begins with <code>_:</code> and that has a
+ path, via properties, that starts with the
+ <a class="tref internalDFN" title="node_reference" href="#dfn-node_reference">node reference</a>.
+ </dd>
+ <dt><dfn title="outgoing_serialization" id="dfn-outgoing_serialization">outgoing serialization</dfn></dt>
+ <dd>
+ A string that can be lexicographically compared to the
+ <a class="tref internalDFN" title="outgoing_serialization" href="#dfn-outgoing_serialization">outgoing serialization</a>s of other
+ <a class="tref internalDFN" title="node_state" href="#dfn-node_state">node state</a>s. It is a representation of the
+ <a class="tref internalDFN" title="outgoing_serialization_map" href="#dfn-outgoing_serialization_map">outgoing serialization map</a> and other related
+ information. This string is initialized to an empty string.
+ </dd>
+ <dt><dfn title="incoming_serialization_map" id="dfn-incoming_serialization_map">incoming serialization map</dfn></dt>
+ <dd>
+ Maps node <a class="tref internalDFN" title="label" href="#dfn-label">label</a>s to <a class="tref internalDFN" title="serialization_label" href="#dfn-serialization_label-1">serialization label</a>s.
+ This map is initialized to an empty map. When this map is populated,
+ it will be filled with keys that are the <a class="tref internalDFN" title="label" href="#dfn-label">label</a>s of every
+ node in the graph with a <a class="tref internalDFN" title="label" href="#dfn-label">label</a> that begins with
+ <code>_:</code> and that has a path, via properties, that ends with
+ the <a class="tref internalDFN" title="node_reference" href="#dfn-node_reference">node reference</a>.
+ </dd>
+ <dt><dfn title="incoming_serialization" id="dfn-incoming_serialization">incoming serialization</dfn></dt>
+ <dd>
+ A string that can be lexicographically compared to the
+ <a class="tref internalDFN" title="outgoing_serialization" href="#dfn-outgoing_serialization">outgoing serialization</a>s of other
+ <a class="tref internalDFN" title="node_state" href="#dfn-node_state">node state</a>s. It is a representation of the
+ <a class="tref internalDFN" title="incoming_serialization_map" href="#dfn-incoming_serialization_map">incoming serialization map</a> and other related
+ information. This string is initialized to an empty string.
+ </dd>
+ </dl>
+ </dd>
+ <dt><dfn title="node_state_map" id="dfn-node_state_map">node state map</dfn></dt>
+ <dd>
+ A mapping from a node's <a class="tref internalDFN" title="label" href="#dfn-label">label</a> to a <a class="tref internalDFN" title="node_state" href="#dfn-node_state">node state</a>.
+ It is initialized to an empty map.
+ </dd>
+ <dt><dfn title="labeling_prefix" id="dfn-labeling_prefix">labeling prefix</dfn></dt>
+ <dd>
+ The labeling prefix is a string that is used as the beginning of a node
+ <a class="tref internalDFN" title="label" href="#dfn-label">label</a>. It should be initialized to a random base string that
+ starts with the characters <code>_:</code>, is not used by any other
+ node's <a class="tref internalDFN" title="label" href="#dfn-label">label</a> in the <a class="tref internalDFN" title="JSON-LD_input" href="#dfn-json-ld_input">JSON-LD input</a>, and does not
+ start with the characters <code>_:c14n</code>. The prefix has two uses.
+ First it is used to temporarily name nodes during the normalization
+ algorithm in a way that doesn't collide with the names that already
+ exist as well as the names that will be generated by the normalization
+ algorithm. Second, it will eventually be set to <code>_:c14n</code> to
+ generate the final, deterministic labels for nodes in the graph. This
+ prefix will be concatenated with the <a class="tref internalDFN" title="labeling_counter" href="#dfn-labeling_counter">labeling counter</a> to
+ produce a node <a class="tref internalDFN" title="label" href="#dfn-label">label</a>. For example, <code>_:j8r3k</code> is
+ a proper initial value for the <a class="tref internalDFN" title="labeling_prefix" href="#dfn-labeling_prefix">labeling prefix</a>.
+ </dd>
+ <dt><dfn title="labeling_counter" id="dfn-labeling_counter">labeling counter</dfn></dt>
+ <dd>
+ A counter that is used to label nodes. It is appended to the
+ <a class="tref internalDFN" title="labeling_prefix" href="#dfn-labeling_prefix">labeling prefix</a> to create a node <a class="tref internalDFN" title="label" href="#dfn-label">label</a>. It is
+ initialized to <code>1</code>.
+ </dd>
+ <dt><dfn title="map_of_flattened_nodes" id="dfn-map_of_flattened_nodes">map of flattened nodes</dfn></dt>
+ <dd>
+ A map containing a representation of all nodes in the graph where the
+ key is a node <a class="tref internalDFN" title="label" href="#dfn-label">label</a> and the value is a single
+ <a class="tref internalDFN" title="JSON_object" href="#dfn-json_object">JSON object</a> that has no nested sub-objects
+ and has had all properties for the same node merged into a single
+ <a class="tref internalDFN" title="JSON_object" href="#dfn-json_object">JSON object</a>.
+ </dd>
+</dl>
+
+</div>
+
+<div id="normalization-algorithm" class="section">
+<h4><span class="secno">3.11.3 </span>Normalization Algorithm</h4>
+
+<p>The normalization algorithm expands the <a class="tref internalDFN" title="JSON-LD_input" href="#dfn-json-ld_input">JSON-LD input</a>,
+flattens the data structure, and creates an initial set of names for all
+nodes in the graph. The flattened data structure is then processed by a
+node labeling algorithm in order to get a fully expanded and named list of
+nodes which is then sorted. The result is a deterministically named and
+ordered list of graph nodes.
+</p>
+
+<ol class="algorithm">
+<li>Expand the <a class="tref internalDFN" title="JSON-LD_input" href="#dfn-json-ld_input">JSON-LD input</a> according to the steps in
+the <a href="#expansion-algorithm">Expansion Algorithm</a> and store the
+result as the <strong>expanded input</strong>.</li>
+<li>Create a <a class="tref internalDFN" title="normalization_state" href="#dfn-normalization_state">normalization state</a>.</li>
+<li>Initialize the <a class="tref internalDFN" title="map_of_flattened_nodes" href="#dfn-map_of_flattened_nodes">map of flattened nodes</a> by recursively
+processing every <dfn title="expanded_node" id="dfn-expanded_node">expanded node</dfn> in the
+<strong>expanded input</strong> in depth-first order:
+ <ol class="algorithm">
+ <li>If the <a class="tref internalDFN" title="expanded_node" href="#dfn-expanded_node">expanded node</a> is an unlabeled node, add a
+ new key-value pair to the <a class="tref internalDFN" title="expanded_node" href="#dfn-expanded_node">expanded node</a>
+ where the key is <code>@subject</code> and the value is the
+ concatenation of the <a class="tref internalDFN" title="labeling_prefix" href="#dfn-labeling_prefix">labeling prefix</a>
+ and the string value of the <a class="tref internalDFN" title="labeling_counter" href="#dfn-labeling_counter">labeling counter</a>.
+ Increment the <a class="tref internalDFN" title="labeling_counter" href="#dfn-labeling_counter">labeling counter</a>.</li>
+ <li>Add the <a class="tref internalDFN" title="expanded_node" href="#dfn-expanded_node">expanded node</a> to the
+ <a class="tref internalDFN" title="map_of_flattened_nodes" href="#dfn-map_of_flattened_nodes">map of flattened nodes</a>:
+ <ol class="algorithm">
+ <li>If the <a class="tref internalDFN" title="expanded_node" href="#dfn-expanded_node">expanded node</a>'s <a class="tref internalDFN" title="label" href="#dfn-label">label</a> is already
+ in the
+ <a class="tref internalDFN" title="map_of_flattened_nodes" href="#dfn-map_of_flattened_nodes">map of flattened nodes</a> merge all properties from the
+ entry in the <a class="tref internalDFN" title="map_of_flattened_nodes" href="#dfn-map_of_flattened_nodes">map of flattened nodes</a> into the
+ <a class="tref internalDFN" title="expanded_node" href="#dfn-expanded_node">expanded node</a>.</li>
+ <li>Go through every property associated with an array in the
+ <a class="tref internalDFN" title="expanded_node" href="#dfn-expanded_node">expanded node</a> and remove any duplicate IRI entries from
+ the array. If the resulting array only has one IRI entry, change it
+ from an array to an object.</li>
+ <li>Set the entry for the <a class="tref internalDFN" title="expanded_node" href="#dfn-expanded_node">expanded node</a>'s <a class="tref internalDFN" title="label" href="#dfn-label">label</a>
+ in the <a class="tref internalDFN" title="map_of_flattened_nodes" href="#dfn-map_of_flattened_nodes">map of flattened nodes</a> to the
+ <a class="tref internalDFN" title="expanded_node" href="#dfn-expanded_node">expanded node</a>.
+ </li></ol></li>
+ <li>After exiting the recursive step, replace the reference to the
+ <a class="tref internalDFN" title="expanded_node" href="#dfn-expanded_node">expanded node</a> with an object containing a single
+ key-value pair where the key is <code>@iri</code> and the value is
+ the value of the <code>@subject</code> key in the node.</li>
+ </ol></li>
+<li>For every entry in the <a class="tref internalDFN" title="map_of_flattened_nodes" href="#dfn-map_of_flattened_nodes">map of flattened nodes</a>, insert a
+ key-value pair into the <a class="tref internalDFN" title="node_state_map" href="#dfn-node_state_map">node state map</a> where the key is the
+ key from the <a class="tref internalDFN" title="map_of_flattened_nodes" href="#dfn-map_of_flattened_nodes">map of flattened nodes</a> and the value is a
+ <a class="tref internalDFN" title="node_state" href="#dfn-node_state">node state</a> where its <a class="tref internalDFN" title="node_reference" href="#dfn-node_reference">node reference</a> refers to
+ the value from the <a class="tref internalDFN" title="map_of_flattened_nodes" href="#dfn-map_of_flattened_nodes">map of flattened nodes</a>.
+</li><li>Populate the <a class="tref internalDFN" title="incoming_list" href="#dfn-incoming_list">incoming list</a> for each <a class="tref internalDFN" title="node_state" href="#dfn-node_state">node state</a>
+ by iterating over every node in the graph and adding its <a class="tref internalDFN" title="label" href="#dfn-label">label</a>
+ to the <a class="tref internalDFN" title="incoming_list" href="#dfn-incoming_list">incoming list</a> associated with each node found in its
+ properties.</li>
+<li>For every entry in the <a class="tref internalDFN" title="node_state_map" href="#dfn-node_state_map">node state map</a> that has a
+<a class="tref internalDFN" title="label" href="#dfn-label">label</a> that begins with <code>_:c14n</code>, relabel the node
+using the <a href="#node-relabeling-algorithm">Node Relabeling Algorithm</a>.
+</li><li>Label all of the nodes that contain a <code>@subject</code> key associated
+with a value starting with <code>_:</code> according to the steps in the
+<a href="#deterministic-labeling-algorithm">Deterministic Labeling Algorithm</a>.
+</li>
+</ol>
+</div>
+
+<div id="node-relabeling-algorithm" class="section">
+<h4><span class="secno">3.11.4 </span>Node Relabeling Algorithm</h4>
+
+<p>This algorithm renames a node by generating a unique
+<dfn title="new_label" id="dfn-new_label">new label</dfn> and updating all references to that <a class="tref internalDFN" title="label" href="#dfn-label">label</a>
+in the <a class="tref internalDFN" title="node_state_map" href="#dfn-node_state_map">node state map</a>. The <dfn title="old_label" id="dfn-old_label">old label</dfn> and the
+<a class="tref internalDFN" title="normalization_state" href="#dfn-normalization_state">normalization state</a> must be given as an input to the
+algorithm. The <a class="tref internalDFN" title="old_label" href="#dfn-old_label">old label</a> is the current <a class="tref internalDFN" title="label" href="#dfn-label">label</a> of
+the node that is to be relabeled.
+
+</p><p>The node relabeling algorithm is as follows:</p>
+
+<ol class="algorithm">
+ <li>If the <a class="tref internalDFN" title="labeling_prefix" href="#dfn-labeling_prefix">labeling prefix</a> is <code>_:c14n</code> and the
+ <a class="tref internalDFN" title="old_label" href="#dfn-old_label">old label</a> begins with <code>_:c14n</code> then return as
+ the node has already been renamed.
+ </li>
+ <li>Generate the <dfn title="new_label" id="dfn-new_label-1">new label</dfn> by concatenating the
+ <a class="tref internalDFN" title="labeling_prefix" href="#dfn-labeling_prefix">labeling prefix</a> with the string value of the
+ <a class="tref internalDFN" title="labeling_counter" href="#dfn-labeling_counter">labeling counter</a>. Increment the <a class="tref internalDFN" title="labeling_counter" href="#dfn-labeling_counter">labeling counter</a>.
+ </li>
+ <li>For the <a class="tref internalDFN" title="node_state" href="#dfn-node_state">node state</a> associated with the
+ <a class="tref internalDFN" title="old_label" href="#dfn-old_label">old label</a>, update every node in the <a class="tref internalDFN" title="incoming_list" href="#dfn-incoming_list">incoming list</a>
+ by changing all the properties that reference the <a class="tref internalDFN" title="old_label" href="#dfn-old_label">old label</a> to
+ the <a class="tref internalDFN" title="new_label" href="#dfn-new_label-1">new label</a>.
+ </li>
+ <li>Change the <a class="tref internalDFN" title="old_label" href="#dfn-old_label">old label</a> key in the <a class="tref internalDFN" title="node_state_map" href="#dfn-node_state_map">node state map</a>
+ to the <a class="tref internalDFN" title="new_label" href="#dfn-new_label-1">new label</a> and set the associated
+ <a class="tref internalDFN" title="node_reference" href="#dfn-node_reference">node reference</a>'s <a class="tref internalDFN" title="label" href="#dfn-label">label</a> to the
+ <a class="tref internalDFN" title="new_label" href="#dfn-new_label-1">new label</a>.
+ </li>
+</ol>
+</div>
+
+<div id="deterministic-labeling-algorithm" class="section">
+<h4><span class="secno">3.11.5 </span>Deterministic Labeling Algorithm</h4>
+
+<p>The deterministic labeling algorithm takes the
+<a class="tref internalDFN" title="normalization_state" href="#dfn-normalization_state">normalization state</a>
+and produces a <dfn title="list_of_finished_nodes" id="dfn-list_of_finished_nodes">list of finished nodes</dfn> that is sorted and
+contains deterministically named and expanded nodes from the graph.
+
+</p><ol class="algorithm">
+ <li>Set the <a class="tref internalDFN" title="labeling_prefix" href="#dfn-labeling_prefix">labeling prefix</a> to <code>_:c14n</code>, the
+ <a class="tref internalDFN" title="labeling_counter" href="#dfn-labeling_counter">labeling counter</a> to <code>1</code>,
+ the <dfn title="list_of_finished_nodes" id="dfn-list_of_finished_nodes-1">list of finished nodes</dfn> to an empty array, and create
+ an empty array, the <dfn title="list_of_unfinished_nodes" id="dfn-list_of_unfinished_nodes">list of unfinished nodes</dfn>.</li>
+ <li>For each <a class="tref internalDFN" title="node_reference" href="#dfn-node_reference">node reference</a> in the <a class="tref internalDFN" title="node_state_map" href="#dfn-node_state_map">node state map</a>:
+ <ol class="algorithm">
+ <li>If the node's <a class="tref internalDFN" title="label" href="#dfn-label">label</a> does not start with <code>_:</code>
+ then put the <a class="tref internalDFN" title="node_reference" href="#dfn-node_reference">node reference</a> in the
+ <a class="tref internalDFN" title="list_of_finished_nodes" href="#dfn-list_of_finished_nodes-1">list of finished nodes</a>.
+ </li>
+ <li>If the node's <a class="tref internalDFN" title="label" href="#dfn-label">label</a> does start with <code>_:</code>
+ then put the <a class="tref internalDFN" title="node_reference" href="#dfn-node_reference">node reference</a> in the
+ <a class="tref internalDFN" title="list_of_unfinished_nodes" href="#dfn-list_of_unfinished_nodes">list of unfinished nodes</a>.
+ </li>
+ </ol>
+ </li>
+ <li>Append to the <a class="tref internalDFN" title="list_of_finished_nodes" href="#dfn-list_of_finished_nodes-1">list of finished nodes</a> by processing
+ the remainder of the <a class="tref internalDFN" title="list_of_unfinished_nodes" href="#dfn-list_of_unfinished_nodes">list of unfinished nodes</a> until it is
+ empty:
+ <ol class="algorithm">
+ <li>Sort the <a class="tref internalDFN" title="list_of_unfinished_nodes" href="#dfn-list_of_unfinished_nodes">list of unfinished nodes</a> in descending order
+ according to the
+ <a href="#deep-comparison-algorithm">Deep Comparison Algorithm</a> to
+ determine the sort order.</li>
+ <li>Create a <dfn title="list_of_labels" id="dfn-list_of_labels">list of labels</dfn> and initialize it to an
+ empty array.</li>
+ <li>For the first node from the <a class="tref internalDFN" title="list_of_unfinished_nodes" href="#dfn-list_of_unfinished_nodes">list of unfinished nodes</a>:
+ <ol class="algorithm">
+ <li>Add its <a class="tref internalDFN" title="label" href="#dfn-label">label</a> to the <a class="tref internalDFN" title="list_of_labels" href="#dfn-list_of_labels">list of labels</a>.
+ </li>
+ <li>For each key-value pair from its associated
+ <a class="tref internalDFN" title="outgoing_serialization_map" href="#dfn-outgoing_serialization_map">outgoing serialization map</a>, add the key to a list and
+ then sort the list according to the lexicographical order of the
+ keys' associated values. Append the list to the
+ <a class="tref" title="list_of_nodes_to_label">list of nodes to label</a>.
+ </li>
+ <li>For each key-value pair from its associated
+ <a class="tref internalDFN" title="incoming_serialization_map" href="#dfn-incoming_serialization_map">incoming serialization map</a>, add the key to a list and
+ then sort the list according to the lexicographical order of the
+ keys' associated values. Append the list to the
+ <a class="tref" title="list_of_nodes_to_label">list of nodes to label</a>.
+ </li></ol></li>
+ <li>For each <a class="tref internalDFN" title="label" href="#dfn-label">label</a> in the <a class="tref internalDFN" title="list_of_labels" href="#dfn-list_of_labels">list of labels</a>,
+ relabel the associated node according to the
+ <a href="#node-relabeling-algorithm">Node Relabeling Algorithm</a>. If
+ any <a class="tref internalDFN" title="outgoing_serialization_map" href="#dfn-outgoing_serialization_map">outgoing serialization map</a> contains a key that
+ matches the <a class="tref internalDFN" title="label" href="#dfn-label">label</a>, clear the map and set the associated
+ <a class="tref internalDFN" title="outgoing_serialization" href="#dfn-outgoing_serialization">outgoing serialization</a> to an empty string. If any
+ <a class="tref internalDFN" title="incoming_serialization_map" href="#dfn-incoming_serialization_map">incoming serialization map</a> contains a key that
+ matches the <a class="tref internalDFN" title="label" href="#dfn-label">label</a>, clear the map and set the associated
+ <a class="tref internalDFN" title="incoming_serialization" href="#dfn-incoming_serialization">incoming serialization</a> to an empty string.
+ </li>
+ <li>
+ Remove each node with a <a class="tref internalDFN" title="label" href="#dfn-label">label</a> that starts with
+ <code>_:c14n</code> from the <a class="tref internalDFN" title="list_of_unfinished_nodes" href="#dfn-list_of_unfinished_nodes">list of unfinished nodes</a> and
+ add it to the <a class="tref internalDFN" title="list_of_finished_nodes" href="#dfn-list_of_finished_nodes-1">list of finished nodes</a>.
+ </li>
+ </ol>
+ </li>
+ <li>Sort the <a class="tref internalDFN" title="list_of_finished_nodes" href="#dfn-list_of_finished_nodes-1">list of finished nodes</a> in descending order
+ according to the
+ <a href="#deep-comparison-algorithm">Deep Comparison Algorithm</a> to
+ determine the sort order.</li>
+</ol>
+</div>
+
+<div id="shallow-comparison-algorithm" class="section">
+<h4><span class="secno">3.11.6 </span>Shallow Comparison Algorithm</h4>
+
+<p>
+The shallow comparison algorithm takes two unlabeled nodes,
+<a class="tref internalDFN" title="alpha" href="#dfn-alpha">alpha</a> and <a class="tref internalDFN" title="beta" href="#dfn-beta">beta</a>, as input and
+determines which one should come first in a sorted list. The following
+algorithm determines the steps that are executed in order to determine the
+node that should come first in a list:
+</p>
+
+<ol class="algorithm">
+ <li>Compare the total number of node properties. The node with fewer
+ properties is first.</li>
+ <li>Lexicographically sort the property IRIs for each node and compare
+ the sorted lists. If an IRI is found to be lexicographically smaller, the
+ node containing that IRI is first.</li>
+ <li>Compare the values of each property against one another:
+ <ol class="algorithm">
+ <li>The node associated with fewer property values is first.
+ </li>
+ <li>Create an <dfn title="alpha_list" id="dfn-alpha_list">alpha list</dfn> by adding all values associated
+ with the <a class="tref internalDFN" title="alpha" href="#dfn-alpha">alpha</a> property that are not unlabeled nodes.
+ </li>
+ <li>Create a <dfn title="beta_list" id="dfn-beta_list">beta list</dfn> by adding all values associated
+ with the <a class="tref internalDFN" title="beta" href="#dfn-beta">beta</a> property that is not an unlabeled node.
+ </li>
+ <li>Compare the length of <a class="tref internalDFN" title="alpha_list" href="#dfn-alpha_list">alpha list</a> and
+ <a class="tref internalDFN" title="beta_list" href="#dfn-beta_list">beta list</a>. The node associated with the list containing
+ the fewer number of items is first.</li>
+ <li>Sort <a class="tref internalDFN" title="alpha_list" href="#dfn-alpha_list">alpha list</a> and <a class="tref internalDFN" title="beta_list" href="#dfn-beta_list">beta list</a> according to
+ the
+ <a href="#object-comparison-algorithm">Object Comparison Algorithm</a>.
+ For each offset into the <a class="tref internalDFN" title="alpha_list" href="#dfn-alpha_list">alpha list</a>, compare the item
+ at the offset against the item at the same offset in the
+ <a class="tref internalDFN" title="beta_list" href="#dfn-beta_list">beta list</a> according to the
+ <a href="#object-comparison-algorithm">Object Comparison Algorithm</a>.
+ The node associated with the lesser item is first.
+ </li></ol></li>
+ <li>Process the <a class="tref internalDFN" title="incoming_list" href="#dfn-incoming_list">incoming list</a>s associated with each node to
+ determine order:
+ <ol class="algorithm">
+ <li>The node with the shortest <a class="tref internalDFN" title="incoming_list" href="#dfn-incoming_list">incoming list</a> is first.</li>
+ <li>Sort the <a class="tref internalDFN" title="incoming_list" href="#dfn-incoming_list">incoming list</a>s according to incoming property
+ and then incoming <a class="tref internalDFN" title="label" href="#dfn-label">label</a>.
+ </li><li>The node associated with the fewest number of incoming nodes is
+ first.</li>
+ <li>For each offset into the <a class="tref internalDFN" title="incoming_list" href="#dfn-incoming_list">incoming list</a>s,
+ compare the associated properties and <a class="tref internalDFN" title="label" href="#dfn-label">label</a>s:
+ <ol class="algorithm">
+ <li>The node associated with a <a class="tref internalDFN" title="label" href="#dfn-label">label</a> that does not begin with
+ <code>_:</code> is first.
+ </li>
+ <li>If the nodes' <a class="tref internalDFN" title="label" href="#dfn-label">label</a>s do not begin with
+ <code>_:</code>, then the node associated with the
+ lexicographically lesser <a class="tref internalDFN" title="label" href="#dfn-label">label</a> is first.</li>
+
+ <li>The node associated with the lexicographically lesser associated
+ property is first.
+ </li>
+ <li>The node with the <a class="tref internalDFN" title="label" href="#dfn-label">label</a> that does not begin with
+ <code>_:c14n</code> is first.
+ </li>
+ <li>The node with the lexicographically lesser <a class="tref internalDFN" title="label" href="#dfn-label">label</a>
+ is first.
+ </li>
+ </ol>
+ </li></ol></li>
+ <li>Otherwise, the nodes are equivalent.</li>
+</ol></div>
+
+<div id="object-comparison-algorithm" class="section">
+<h4><span class="secno">3.11.7 </span>Object Comparison Algorithm</h4>
+
+<p>
+The object comparison algorithm is designed to compare two graph node
+property values, <a class="tref internalDFN" title="alpha" href="#dfn-alpha">alpha</a> and <a class="tref internalDFN" title="beta" href="#dfn-beta">beta</a>, against the other.
+The algorithm is useful when sorting two lists of graph node properties.
+</p>
+
+<ol class="algorithm">
+ <li>If one of the values is a <a class="tref internalDFN" title="string" href="#dfn-string">string</a> and the other is not, the value that is
+ a string is first.
+ </li>
+ <li>If both values are <a class="tref internalDFN" title="string" href="#dfn-string">string</a>s, the lexicographically lesser string is
+ first.
+ </li>
+ <li>If one of the values is a literal and the other is not, the value that is
+ a literal is first.
+ </li>
+ <li>If both values are literals:
+ <ol class="algorithm">
+ <li>The lexicographically lesser string associated with
+ <code>@literal</code> is first.
+ </li>
+ <li>The lexicographically lesser string associated with
+ <code>@datatype</code> is first.
+ </li>
+ <li>The lexicographically lesser string associated with
+ <code>@language</code> is first.
+ </li>
+ </ol>
+ </li>
+ <li>If both values are expanded IRIs, the
+ lexicographically lesser string associated with <code>@iri</code>
+ is first.</li>
+ <li>Otherwise, the two values are equivalent.</li>
+</ol>
+
+</div>
+
+<div id="deep-comparison-algorithm" class="section">
+<h4><span class="secno">3.11.8 </span>Deep Comparison Algorithm</h4>
+
+<p>
+The deep comparison algorithm is used to compare the difference between two
+nodes, <a class="tref internalDFN" title="alpha" href="#dfn-alpha">alpha</a> and <a class="tref internalDFN" title="beta" href="#dfn-beta">beta</a>.
+A deep comparison takes the incoming and outgoing node edges in
+a graph into account if the number of properties and value of those properties
+are identical. The algorithm is helpful when sorting a list of nodes and will
+return whichever node should be placed first in a list if the two nodes are
+not truly equivalent.
+</p>
+
+<p>When performing the steps required by the deep comparison algorithm, it
+is helpful to track state information about mappings. The information
+contained in a <a class="tref internalDFN" title="mapping_state" href="#dfn-mapping_state">mapping state</a> is described below.</p>
+
+<dl class="algorithm">
+ <dt><dfn title="mapping_state" id="dfn-mapping_state">mapping state</dfn></dt>
+ <dd>
+ <dl>
+ <dt><dfn title="mapping_counter" id="dfn-mapping_counter">mapping counter</dfn></dt>
+ <dd>
+ Keeps track of the number of nodes that have been mapped to
+ <a class="tref" title="serialization_labels">serialization labels</a>. It is initialized to
+ <code>1</code>.
+ </dd>
+ <dt><dfn title="processed_labels_map" id="dfn-processed_labels_map">processed labels map</dfn></dt>
+ <dd>
+ Keeps track of the <a class="tref internalDFN" title="label" href="#dfn-label">label</a>s of nodes that have already
+ been assigned <a class="tref internalDFN" title="serialization_label" href="#dfn-serialization_label-1">serialization label</a>s. It is initialized
+ to an empty map.
+ </dd>
+ <dt><dfn title="serialized_labels_map" id="dfn-serialized_labels_map">serialized labels map</dfn></dt>
+ <dd>
+ Maps a node <a class="tref internalDFN" title="label" href="#dfn-label">label</a> to its associated
+ <a class="tref internalDFN" title="serialization_label" href="#dfn-serialization_label-1">serialization label</a>. It is initialized to an empty map.
+ </dd>
+ <dt><dfn title="adjacent_info_map" id="dfn-adjacent_info_map">adjacent info map</dfn></dt>
+ <dd>
+ Maps a <a class="tref internalDFN" title="serialization_label" href="#dfn-serialization_label-1">serialization label</a> to the node
+ <a class="tref internalDFN" title="label" href="#dfn-label">label</a> associated with it, the list of sorted
+ <a class="tref internalDFN" title="serialization_label" href="#dfn-serialization_label-1">serialization label</a>s for adjacent nodes, and the map of
+ adjacent node <a class="tref" title="serialiation_label">serialiation label</a>s to their associated
+ node <a class="tref internalDFN" title="label" href="#dfn-label">label</a>s. It is initialized to an empty map.
+ </dd>
+ <dt><dfn title="key_stack" id="dfn-key_stack">key stack</dfn></dt>
+ <dd>
+ A stack where each element contains an array of adjacent
+ <a class="tref internalDFN" title="serialization_label" href="#dfn-serialization_label-1">serialization label</a>s and an index into that array. It
+ is initialized to a stack containing a single element where its
+ array contains a single string element <code>s1</code> and its
+ index is set to <code>0</code>.
+ </dd>
+ <dt><dfn title="serialized_keys" id="dfn-serialized_keys">serialized keys</dfn></dt>
+ <dd>
+ Keeps track of which <a class="tref internalDFN" title="serialization_label" href="#dfn-serialization_label-1">serialization label</a>s have already
+ been written at least once to the <a class="tref internalDFN" title="serialization_string" href="#dfn-serialization_string">serialization string</a>.
+ It is initialized to an empty map.
+ </dd>
+ <dt><dfn title="serialization_string" id="dfn-serialization_string">serialization string</dfn></dt>
+ <dd>
+ A string that is incrementally updated as a serialization is built.
+ It is initialized to an empty string.
+ </dd>
+ </dl>
+ </dd>
+</dl>
+
+<p>The deep comparison algorithm is as follows:</p>
+
+<ol class="algorithm">
+ <li>Perform a comparison between <a class="tref internalDFN" title="alpha" href="#dfn-alpha">alpha</a> and <a class="tref internalDFN" title="beta" href="#dfn-beta">beta</a>
+ according to the
+ <a href="#shallow-comparison-algorithm">Shallow Comparison Algorithm</a>.
+ If the result does not show that the two nodes are equivalent, return
+ the result.
+ </li>
+ <li>Compare incoming and outgoing edges for each node, updating their
+ associated <a class="tref internalDFN" title="node_state" href="#dfn-node_state">node state</a> as each node is processed:
+ <ol class="algorithm">
+ <li>If the <a class="tref internalDFN" title="outgoing_serialization_map" href="#dfn-outgoing_serialization_map">outgoing serialization map</a> for <a class="tref internalDFN" title="alpha" href="#dfn-alpha">alpha</a>
+ is empty, generate the serialization according to the
+ <a href="#node-serialization-algorithm">Node Serialization Algorithm</a>.
+ Provide <a class="tref internalDFN" title="alpha" href="#dfn-alpha">alpha</a>'s <a class="tref internalDFN" title="node_state" href="#dfn-node_state">node state</a>, a new
+ <a class="tref internalDFN" title="mapping_state" href="#dfn-mapping_state">mapping state</a>,
+ <code>outgoing direction</code> to the algorithm as inputs.
+ </li><li>If the <a class="tref internalDFN" title="outgoing_serialization_map" href="#dfn-outgoing_serialization_map">outgoing serialization map</a> for <a class="tref internalDFN" title="beta" href="#dfn-beta">beta</a>
+ is empty, generate the serialization according to the
+ <a href="#node-serialization-algorithm">Node Serialization Algorithm</a>.
+ Provide <a class="tref internalDFN" title="beta" href="#dfn-beta">beta</a>'s <a class="tref internalDFN" title="node_state" href="#dfn-node_state">node state</a>, a new
+ <a class="tref internalDFN" title="mapping_state" href="#dfn-mapping_state">mapping state</a>, and
+ <code>outgoing direction</code> to the algorithm as inputs.
+ </li><li>If <a class="tref internalDFN" title="alpha" href="#dfn-alpha">alpha</a>'s <a class="tref internalDFN" title="outgoing_serialization" href="#dfn-outgoing_serialization">outgoing serialization</a> is
+ lexicographically less than <a class="tref internalDFN" title="beta" href="#dfn-beta">beta</a>'s, then
+ <a class="tref internalDFN" title="alpha" href="#dfn-alpha">alpha</a> is first. If it is greater, then <a class="tref internalDFN" title="beta" href="#dfn-beta">beta</a>
+ is first.</li>
+ <li>If the <a class="tref internalDFN" title="incoming_serialization_map" href="#dfn-incoming_serialization_map">incoming serialization map</a> for <a class="tref internalDFN" title="alpha" href="#dfn-alpha">alpha</a>
+ is empty, generate the serialization according to the
+ <a href="#node-serialization-algorithm">Node Serialization Algorithm</a>.
+ Provide <a class="tref internalDFN" title="alpha" href="#dfn-alpha">alpha</a>'s <a class="tref internalDFN" title="node_state" href="#dfn-node_state">node state</a>, a new
+ <a class="tref internalDFN" title="mapping_state" href="#dfn-mapping_state">mapping state</a> with its <a class="tref internalDFN" title="serialized_labels_map" href="#dfn-serialized_labels_map">serialized labels map</a>
+ set to a copy of <a class="tref internalDFN" title="alpha" href="#dfn-alpha">alpha</a>'s
+ <a class="tref internalDFN" title="outgoing_serialization_map" href="#dfn-outgoing_serialization_map">outgoing serialization map</a>, and
+ <code>incoming direction</code> to the algorithm as inputs.
+ </li><li>If the <a class="tref internalDFN" title="incoming_serialization_map" href="#dfn-incoming_serialization_map">incoming serialization map</a> for <a class="tref internalDFN" title="beta" href="#dfn-beta">beta</a>
+ is empty, generate the serialization according to the
+ <a href="#node-serialization-algorithm">Node Serialization Algorithm</a>.
+ Provide <a class="tref internalDFN" title="beta" href="#dfn-beta">beta</a>'s <a class="tref internalDFN" title="node_state" href="#dfn-node_state">node state</a>, a new
+ <a class="tref internalDFN" title="mapping_state" href="#dfn-mapping_state">mapping state</a> with its <a class="tref internalDFN" title="serialized_labels_map" href="#dfn-serialized_labels_map">serialized labels map</a>
+ set to a copy of <a class="tref internalDFN" title="beta" href="#dfn-beta">beta</a>'s
+ <a class="tref internalDFN" title="outgoing_serialization_map" href="#dfn-outgoing_serialization_map">outgoing serialization map</a>, and
+ <code>incoming direction</code> to the algorithm as inputs.
+ </li><li>If <a class="tref internalDFN" title="alpha" href="#dfn-alpha">alpha</a>'s <a class="tref internalDFN" title="incoming_serialization" href="#dfn-incoming_serialization">incoming serialization</a> is
+ lexicographically less than <a class="tref internalDFN" title="beta" href="#dfn-beta">beta</a>'s, then
+ <a class="tref internalDFN" title="alpha" href="#dfn-alpha">alpha</a> is first. If it is greater, then <a class="tref internalDFN" title="beta" href="#dfn-beta">beta</a>
+ is first.</li>
+ </ol></li>
+</ol>
+</div>
+
+<div id="node-serialization-algorithm" class="section">
+<h4><span class="secno">3.11.9 </span>Node Serialization Algorithm</h4>
+
+<p>
+The node serialization algorithm takes a <a class="tref internalDFN" title="node_state" href="#dfn-node_state">node state</a>, a
+<a class="tref internalDFN" title="mapping_state" href="#dfn-mapping_state">mapping state</a>, and a <dfn title="direction" id="dfn-direction">direction</dfn> (either
+<code>outgoing direction</code> or <code>incoming direction</code>) as
+inputs and generates a deterministic serialization for the
+<a class="tref internalDFN" title="node_reference" href="#dfn-node_reference">node reference</a>.
+</p>
+
+<ol class="algorithm">
+<li>If the <a class="tref internalDFN" title="label" href="#dfn-label">label</a> exists in the
+ <a class="tref internalDFN" title="processed_labels_map" href="#dfn-processed_labels_map">processed labels map</a>, terminate the algorithm as the
+ <a class="tref internalDFN" title="serialization_label" href="#dfn-serialization_label-1">serialization label</a> has already been created.
+</li>
+<li>Set the value associated with the <a class="tref internalDFN" title="label" href="#dfn-label">label</a> in the
+ <a class="tref internalDFN" title="processed_labels_map" href="#dfn-processed_labels_map">processed labels map</a> to <code>true</code>.
+</li>
+<li>Generate the next <dfn title="serialization_label" id="dfn-serialization_label-1">serialization label</dfn> for the
+ <a class="tref internalDFN" title="label" href="#dfn-label">label</a> according to the
+ <a href="#serialization-label-generation-algorithm">Serialization Label Generation Algorithm</a>.
+</li>
+<li>Create an empty map called the <dfn title="adjacent_serialized_labels_map" id="dfn-adjacent_serialized_labels_map">adjacent serialized labels map</dfn>
+that will store mappings from <a class="tref" title="serialized_label">serialized label</a>s to adjacent
+node <a class="tref internalDFN" title="label" href="#dfn-label">label</a>s.</li>
+<li>Create an empty array called the
+<dfn title="adjacent_unserialized_labels_list" id="dfn-adjacent_unserialized_labels_list">adjacent unserialized labels list</dfn> that will store
+<a class="tref internalDFN" title="label" href="#dfn-label">label</a>s of adjacent nodes that haven't been assigned
+<a class="tref internalDFN" title="serialization_label" href="#dfn-serialization_label-1">serialization label</a>s yet.
+</li>
+<li>For every <a class="tref internalDFN" title="label" href="#dfn-label">label</a> in a list, where the list the <a class="tref internalDFN" title="outgoing_list" href="#dfn-outgoing_list">outgoing list</a> if
+the <a class="tref internalDFN" title="direction" href="#dfn-direction">direction</a> is <code>outgoing direction</code> and the
+<a class="tref internalDFN" title="incoming_list" href="#dfn-incoming_list">incoming list</a> otherwise, if the <a class="tref internalDFN" title="label" href="#dfn-label">label</a> starts with
+<code>_:</code>, it is the <dfn title="target_node_label" id="dfn-target_node_label">target node label</dfn>:
+ <ol class="algorithm">
+ <li>Look up the <a class="tref internalDFN" title="target_node_label" href="#dfn-target_node_label">target node label</a> in the
+ <a class="tref internalDFN" title="processed_labels_map" href="#dfn-processed_labels_map">processed labels map</a> and if a mapping exists,
+ update the <a class="tref internalDFN" title="adjacent_serialized_labels_map" href="#dfn-adjacent_serialized_labels_map">adjacent serialized labels map</a> where the key is
+ the value in the <a class="tref" title="serialization_map">serialization map</a> and the value is the
+ <a class="tref internalDFN" title="target_node_label" href="#dfn-target_node_label">target node label</a>.</li>
+ <li>Otherwise, add the <a class="tref internalDFN" title="target_node_label" href="#dfn-target_node_label">target node label</a> to the
+ <a class="tref internalDFN" title="adjacent_unserialized_labels_list" href="#dfn-adjacent_unserialized_labels_list">adjacent unserialized labels list</a>.
+ </li></ol>
+</li>
+<li>Set the <dfn title="maximum_serialization_combinations" id="dfn-maximum_serialization_combinations">maximum serialization combinations</dfn> to
+ <code>1</code> or the length of the
+ <a class="tref internalDFN" title="adjacent_unserialized_labels_list" href="#dfn-adjacent_unserialized_labels_list">adjacent unserialized labels list</a>, whichever is greater.</li>
+<li>While the <a class="tref internalDFN" title="maximum_serialization_combinations" href="#dfn-maximum_serialization_combinations">maximum serialization combinations</a> is greater than
+ <code>0</code>, perform the
+ <a href="#combinatorial-serialization-algorithm">Combinatorial Serialization Algorithm</a>
+ passing the <a class="tref internalDFN" title="node_state" href="#dfn-node_state">node state</a>, the <a class="tref internalDFN" title="mapping_state" href="#dfn-mapping_state">mapping state</a> for the
+ first iteration and a copy of it for each subsequent iteration, the
+ generated <a class="tref internalDFN" title="serialization_label" href="#dfn-serialization_label-1">serialization label</a>, the <a class="tref internalDFN" title="direction" href="#dfn-direction">direction</a>,
+ the <a class="tref internalDFN" title="adjacent_serialized_labels_map" href="#dfn-adjacent_serialized_labels_map">adjacent serialized labels map</a>, and the
+ <a class="tref internalDFN" title="adjacent_unserialized_labels_list" href="#dfn-adjacent_unserialized_labels_list">adjacent unserialized labels list</a>.
+ Decrement the <a class="tref internalDFN" title="maximum_serialization_combinations" href="#dfn-maximum_serialization_combinations">maximum serialization combinations</a> by
+ <code>1</code> for each iteration.
+</li></ol>
+
+</div>
+
+<div id="serialization-label-generation-algorithm" class="section">
+<h4><span class="secno">3.11.10 </span>Serialization Label Generation Algorithm</h4>
+
+<p>
+The algorithm generates a <a class="tref internalDFN" title="serialization_label" href="#dfn-serialization_label-1">serialization label</a> given a
+<a class="tref internalDFN" title="label" href="#dfn-label">label</a> and a <a class="tref internalDFN" title="mapping_state" href="#dfn-mapping_state">mapping state</a> and returns the
+<a class="tref internalDFN" title="serialization_label" href="#dfn-serialization_label-1">serialization label</a>.
+</p>
+
+ <ol class="algorithm">
+ <li>If the <a class="tref internalDFN" title="label" href="#dfn-label">label</a> is already in the
+ <a class="tref" title="serialization_labels_map">serialization labels map</a>, return its associated value.
+ </li>
+ <li>If the <a class="tref internalDFN" title="label" href="#dfn-label">label</a> starts with the string <code>_:c14n</code>,
+ the <a class="tref internalDFN" title="serialization_label" href="#dfn-serialization_label-1">serialization label</a> is the letter <code>c</code>
+ followed by the number that follows <code>_:c14n</code> in the
+ <a class="tref internalDFN" title="label" href="#dfn-label">label</a>.
+ </li>
+ <li>Otherwise, the <a class="tref internalDFN" title="serialization_label" href="#dfn-serialization_label-1">serialization label</a> is the
+ letter <code>s</code> followed by the string value of
+ <a class="tref" title="mapping_count">mapping count</a>. Increment the <a class="tref" title="mapping_count">mapping count</a> by
+ <code>1</code>.
+ </li>
+ <li>Create a new key-value pair in the <a class="tref" title="serialization_labels_map">serialization labels map</a>
+ where the key is the <a class="tref internalDFN" title="label" href="#dfn-label">label</a> and the value is the
+ generated <a class="tref internalDFN" title="serialization_label" href="#dfn-serialization_label-1">serialization label</a>.
+ </li>
+ </ol>
+</div>
+
+<div id="combinatorial-serialization-algorithm" class="section">
+<h4><span class="secno">3.11.11 </span>Combinatorial Serialization Algorithm</h4>
+
+<p>
+The combinatorial serialization algorithm takes a <a class="tref internalDFN" title="node_state" href="#dfn-node_state">node state</a>, a
+<a class="tref internalDFN" title="mapping_state" href="#dfn-mapping_state">mapping state</a>, a <a class="tref internalDFN" title="serialization_label" href="#dfn-serialization_label-1">serialization label</a>, a
+<a class="tref internalDFN" title="direction" href="#dfn-direction">direction</a>, a <a class="tref internalDFN" title="adjacent_serialized_labels_map" href="#dfn-adjacent_serialized_labels_map">adjacent serialized labels map</a>,
+and a <a class="tref internalDFN" title="adjacent_unserialized_labels_list" href="#dfn-adjacent_unserialized_labels_list">adjacent unserialized labels list</a> as inputs and generates
+the lexicographically least serialization of nodes relating to the
+<a class="tref internalDFN" title="node_reference" href="#dfn-node_reference">node reference</a>.
+</p>
+
+<ol class="algorithm">
+ <li>If the <a class="tref internalDFN" title="adjacent_unserialized_labels_list" href="#dfn-adjacent_unserialized_labels_list">adjacent unserialized labels list</a> is not empty:
+ <ol class="algorithm">
+ <li>Copy the <a class="tref internalDFN" title="adjacent_serialized_labels_map" href="#dfn-adjacent_serialized_labels_map">adjacent serialized labels map</a> to the
+ <dfn title="adjacent_serialized_labels_map_copy" id="dfn-adjacent_serialized_labels_map_copy">adjacent serialized labels map copy</dfn>.</li>
+ <li>Remove the first <a class="tref" title="unserialized_label">unserialized label</a> from the
+ <a class="tref internalDFN" title="adjacent_unserialized_labels_list" href="#dfn-adjacent_unserialized_labels_list">adjacent unserialized labels list</a> and create a new
+ <dfn title="new_serialization_label" id="dfn-new_serialization_label">new serialization label</dfn> according to the
+ <a href="#serialization-label-generation-algorithm">Serialization Label Generation Algorithm</a>.
+ </li><li>Create a new key-value mapping in the
+ <a class="tref internalDFN" title="adjacent_serialized_labels_map_copy" href="#dfn-adjacent_serialized_labels_map_copy">adjacent serialized labels map copy</a>
+ where the key is the <a class="tref internalDFN" title="new_serialization_label" href="#dfn-new_serialization_label">new serialization label</a> and the value
+ is the <a class="tref" title="unserialized_label">unserialized label</a>.
+ </li><li>Set the <dfn title="maximum_serialization_rotations" id="dfn-maximum_serialization_rotations">maximum serialization rotations</dfn> to
+ <code>1</code> or the length of the
+ <a class="tref internalDFN" title="adjacent_unserialized_labels_list" href="#dfn-adjacent_unserialized_labels_list">adjacent unserialized labels list</a>, whichever is greater.
+ </li>
+ <li>While the <a class="tref internalDFN" title="maximum_serialization_rotations" href="#dfn-maximum_serialization_rotations">maximum serialization rotations</a> is greater than
+ <code>0</code>:
+ <ol class="algorithm">
+ <li>Recursively perform the
+ <a href="#combinatorial-serialization-algorithm">Combinatorial Serialization Algorithm</a>
+ passing the <a class="tref internalDFN" title="mapping_state" href="#dfn-mapping_state">mapping state</a> for the first iteration of the
+ loop, and a copy of it for each subsequent iteration.
+ </li>
+ <li>Rotate the elements in the
+ <a class="tref internalDFN" title="adjacent_unserialized_labels_list" href="#dfn-adjacent_unserialized_labels_list">adjacent unserialized labels list</a> by shifting each of
+ them once to the right, moving the element at the end of the list
+ to the beginning of the list.
+ </li>
+ <li>Decrement the <a class="tref internalDFN" title="maximum_serialization_rotations" href="#dfn-maximum_serialization_rotations">maximum serialization rotations</a> by
+ <code>1</code> for each iteration.
+ </li>
+ </ol>
+ </li>
+ </ol>
+ </li>
+ <li>If the <a class="tref internalDFN" title="adjacent_unserialized_labels_list" href="#dfn-adjacent_unserialized_labels_list">adjacent unserialized labels list</a> is empty:
+ <ol class="algorithm">
+ <li>Create a <dfn title="list_of_keys" id="dfn-list_of_keys">list of keys</dfn> from the keys in the
+ <a class="tref internalDFN" title="adjacent_serialized_labels_map" href="#dfn-adjacent_serialized_labels_map">adjacent serialized labels map</a> and sort it
+ lexicographically.
+ </li>
+ <li>Add a key-value pair to the <a class="tref internalDFN" title="adjacent_info_map" href="#dfn-adjacent_info_map">adjacent info map</a> where
+ the key is the <a class="tref internalDFN" title="serialization_label" href="#dfn-serialization_label-1">serialization label</a> and the value is
+ an object containing the <a class="tref internalDFN" title="node_reference" href="#dfn-node_reference">node reference</a>'s label, the
+ <a class="tref internalDFN" title="list_of_keys" href="#dfn-list_of_keys">list of keys</a> and the
+ <a class="tref internalDFN" title="adjacent_serialized_labels_map" href="#dfn-adjacent_serialized_labels_map">adjacent serialized labels map</a>.
+ </li>
+ <li>Update the <a class="tref internalDFN" title="serialization_string" href="#dfn-serialization_string">serialization string</a> according to the
+ <a href="#mapping-serialization-algorithm">Mapping Serialization Algorithm</a>.
+ </li>
+ <li>If the <a class="tref internalDFN" title="direction" href="#dfn-direction">direction</a> is <code>outgoing direction</code>
+ then <dfn title="directed_serialization" id="dfn-directed_serialization">directed serialization</dfn> refers to the
+ <a class="tref internalDFN" title="outgoing_serialization" href="#dfn-outgoing_serialization">outgoing serialization</a> and the
+ <dfn title="directed_serialization_map" id="dfn-directed_serialization_map">directed serialization map</dfn> refers to the
+ <a class="tref internalDFN" title="outgoing_serialization_map" href="#dfn-outgoing_serialization_map">outgoing serialization map</a>, otherwise it refers to the
+ <a class="tref internalDFN" title="incoming_serialization" href="#dfn-incoming_serialization">incoming serialization</a> and the
+ <a class="tref internalDFN" title="directed_serialization_map" href="#dfn-directed_serialization_map">directed serialization map</a> refers to the
+ <a class="tref internalDFN" title="incoming_serialization_map" href="#dfn-incoming_serialization_map">incoming serialization map</a>. Compare the
+ <a class="tref internalDFN" title="serialization_string" href="#dfn-serialization_string">serialization string</a> to the
+ <a class="tref internalDFN" title="directed_serialization" href="#dfn-directed_serialization">directed serialization</a> according to the
+ <a href="#mapping-serialization-algorithm">Serialization Comparison Algorithm</a>.
+ If the <a class="tref internalDFN" title="serialization_string" href="#dfn-serialization_string">serialization string</a> is less than or equal to
+ the <a class="tref internalDFN" title="directed_serialization" href="#dfn-directed_serialization">directed serialization</a>:
+ <ol class="algorithm">
+ <li>For each value in the <a class="tref internalDFN" title="list_of_keys" href="#dfn-list_of_keys">list of keys</a>, run the
+ <a href="#node-serialization-algorithm">Node Serialization Algorithm</a>.
+ </li>
+ <li>Update the <a class="tref internalDFN" title="serialization_string" href="#dfn-serialization_string">serialization string</a> according to the
+ <a href="#mapping-serialization-algorithm">Mapping Serialization Algorithm</a>.
+ </li>
+ <li>Compare the <a class="tref internalDFN" title="serialization_string" href="#dfn-serialization_string">serialization string</a> to the
+ <a class="tref internalDFN" title="directed_serialization" href="#dfn-directed_serialization">directed serialization</a> again and if it is less than
+ or equal and the length of the <a class="tref internalDFN" title="serialization_string" href="#dfn-serialization_string">serialization string</a> is
+ greater than or equal to the length of the
+ <a class="tref internalDFN" title="directed_serialization" href="#dfn-directed_serialization">directed serialization</a>, then set the
+ <a class="tref internalDFN" title="directed_serialization" href="#dfn-directed_serialization">directed serialization</a> to the
+ <a class="tref internalDFN" title="serialization_string" href="#dfn-serialization_string">serialization string</a> and set the
+ <a class="tref internalDFN" title="directed_serialization_map" href="#dfn-directed_serialization_map">directed serialization map</a> to the
+ <a class="tref internalDFN" title="serialized_labels_map" href="#dfn-serialized_labels_map">serialized labels map</a>.
+ </li>
+ </ol>
+ </li>
+ </ol>
+ </li>
+</ol>
+
+</div>
+
+<div id="serialization-comparison-algorithm" class="section">
+<h4><span class="secno">3.11.12 </span>Serialization Comparison Algorithm</h4>
+
+<p>
+The serialization comparison algorithm takes two serializations,
+<a class="tref internalDFN" title="alpha" href="#dfn-alpha">alpha</a> and <a class="tref internalDFN" title="beta" href="#dfn-beta">beta</a> and returns either which of the two
+is less than the other or that they are equal.
+</p>
+
+<ol class="algorithm">
+ <li>Whichever serialization is an empty string is greater. If they are
+ both empty strings, they are equal.</li>
+ <li>Return the result of a lexicographical comparison of <a class="tref internalDFN" title="alpha" href="#dfn-alpha">alpha</a>
+ and <a class="tref internalDFN" title="beta" href="#dfn-beta">beta</a> up to the number of characters in the shortest of
+ the two serializations.
+ </li>
+</ol>
+</div>
+
+<div id="mapping-serialization-algorithm" class="section">
+<h4><span class="secno">3.11.13 </span>Mapping Serialization Algorithm</h4>
+
+<p>
+The mapping serialization algorithm incrementally updates the
+<a class="tref internalDFN" title="serialization_string" href="#dfn-serialization_string">serialization string</a> in a <a class="tref internalDFN" title="mapping_state" href="#dfn-mapping_state">mapping state</a>.
+</p>
+
+<ol class="algorithm">
+ <li>If the <a class="tref internalDFN" title="key_stack" href="#dfn-key_stack">key stack</a> is not empty:
+ <ol class="algorithm">
+ <li>Pop the <dfn title="serialization_key_info" id="dfn-serialization_key_info">serialization key info</dfn> off of the
+ <a class="tref internalDFN" title="key_stack" href="#dfn-key_stack">key stack</a>.
+ </li>
+ <li>For each <dfn title="serialization_key" id="dfn-serialization_key">serialization key</dfn> in the
+ <a class="tref internalDFN" title="serialization_key_info" href="#dfn-serialization_key_info">serialization key info</a> array, starting at
+ the <dfn title="serialization_key_index" id="dfn-serialization_key_index">serialization key index</dfn> from the
+ <a class="tref internalDFN" title="serialization_key_info" href="#dfn-serialization_key_info">serialization key info</a>:
+ <ol class="algorithm">
+ <li>If the <a class="tref internalDFN" title="serialization_key" href="#dfn-serialization_key">serialization key</a> is not in the
+ <a class="tref internalDFN" title="adjacent_info_map" href="#dfn-adjacent_info_map">adjacent info map</a>, push the
+ <a class="tref internalDFN" title="serialization_key_info" href="#dfn-serialization_key_info">serialization key info</a> onto the
+ <a class="tref internalDFN" title="key_stack" href="#dfn-key_stack">key stack</a> and exit from this loop.
+ </li>
+ <li>If the <a class="tref internalDFN" title="serialization_key" href="#dfn-serialization_key">serialization key</a> is a key in
+ <a class="tref internalDFN" title="serialized_keys" href="#dfn-serialized_keys">serialized keys</a>, a cycle has been detected. Append
+ the concatenation of the <code>_</code> character and the
+ <a class="tref internalDFN" title="serialization_key" href="#dfn-serialization_key">serialization key</a> to the
+ <a class="tref internalDFN" title="serialization_string" href="#dfn-serialization_string">serialization string</a>.
+ </li><li>Otherwise, serialize all outgoing and incoming edges in the
+ related node by performing the following steps:
+ <ol class="algorithm">
+ <li>Mark the <a class="tref internalDFN" title="serialization_key" href="#dfn-serialization_key">serialization key</a> as having
+ been processed by adding a new key-value pair to
+ <a class="tref internalDFN" title="serialized_keys" href="#dfn-serialized_keys">serialized keys</a> where the key
+ is the <a class="tref internalDFN" title="serialization_key" href="#dfn-serialization_key">serialization key</a> and the value is
+ <code>true</code>.
+ </li>
+ <li>Set the <dfn title="serialization_fragment" id="dfn-serialization_fragment">serialization fragment</dfn> to the value of
+ the <a class="tref internalDFN" title="serialization_key" href="#dfn-serialization_key">serialization key</a>.</li>
+ <li>Set the <a class="tref" title="adjacent_info">adjacent info</a> to the value of the
+ <a class="tref internalDFN" title="serialization_key" href="#dfn-serialization_key">serialization key</a> in the
+ <a class="tref internalDFN" title="adjacent_info_map" href="#dfn-adjacent_info_map">adjacent info map</a>.
+ </li>
+ <li>Set the <a class="tref" title="adjacent_node_label">adjacent node label</a> to the node
+ <a class="tref internalDFN" title="label" href="#dfn-label">label</a> from the <a class="tref" title="adjacent_info">adjacent info</a>.
+ </li>
+ <li>If a mapping for the <a class="tref" title="adjacent_node_label">adjacent node label</a>
+ exists in the <a class="tref" title="map_of_all_labels">map of all labels</a>:
+ <ol class="algorithm">
+ <li>Append the result of the
+ <a href="">Label Serialization Algorithm</a> to the
+ <a class="tref internalDFN" title="serialization_fragment" href="#dfn-serialization_fragment">serialization fragment</a>.
+ </li>
+ </ol>
+ </li>
+ <li>Append all of the keys in the <a class="tref" title="adjacent_info">adjacent info</a>
+ to the <a class="tref internalDFN" title="serialization_fragment" href="#dfn-serialization_fragment">serialization fragment</a>.
+ </li>
+ <li>Append the <a class="tref internalDFN" title="serialization_fragment" href="#dfn-serialization_fragment">serialization fragment</a> to the
+ <a class="tref internalDFN" title="serialization_string" href="#dfn-serialization_string">serialization string</a>.
+ </li>
+ <li>Push a new key info object containing the keys from the
+ <a class="tref" title="adjacent_info">adjacent info</a> and an index of <code>0</code>
+ onto the <a class="tref internalDFN" title="key_stack" href="#dfn-key_stack">key stack</a>.
+ </li>
+ <li>Recursively update the <a class="tref internalDFN" title="serialization_string" href="#dfn-serialization_string">serialization string</a>
+ according to the
+ <a href="#mapping-serialization-algorithm">Mapping Serialization Algorithm</a>.
+ </li>
+ </ol>
+ </li>
+ </ol>
+ </li>
+ </ol>
+ </li>
+</ol>
+
+</div>
+
+<div id="label-serialization-algorithm" class="section">
+<h4><span class="secno">3.11.14 </span>Label Serialization Algorithm</h4>
+
+<p>
+The label serialization algorithm serializes information about a node that
+has been assigned a particular <a class="tref internalDFN" title="serialization_label" href="#dfn-serialization_label-1">serialization label</a>.
+</p>
+
+<ol class="algorithm">
+ <li>Initialize the <a class="tref" title="label_serialization">label serialization</a> to an empty string.</li>
+ <li>Append the <code>[</code> character to the
+ <a class="tref" title="label_serialization">label serialization</a>.</li>
+ <li>Append all properties to the <a class="tref" title="label_serialization">label serialization</a> by
+ processing each key-value pair in the <a class="tref internalDFN" title="node_reference" href="#dfn-node_reference">node reference</a>,
+ excluding the
+ <code>@subject</code> property. The keys should be processed in
+ lexicographical order and their associated values should be processed
+ in the order produced by the
+ <a href="#object-comparison-algorithm">Object Comparison Algorithm</a>:
+ <ol class="algorithm">
+ <li>Build a string using the pattern <code><</code><strong>KEY</strong><code>></code>
+ where <strong>KEY</strong> is the current key. Append string to the
+ <a class="tref" title="label_serialization">label serialization</a>.</li>
+ <li>The value may be a single object or an array of objects.
+ Process all of the objects that are associated with the key, building
+ an <dfn title="object_string" id="dfn-object_string">object string</dfn> for each item:
+ <ol class="algorithm">
+ <li>If the object contains an <code>@iri</code> key with a
+ value that starts
+ with <code>_:</code>, set the <a class="tref internalDFN" title="object_string" href="#dfn-object_string">object string</a> to
+ the value <code>_:</code>. If the value does not
+ start with <code>_:</code>, build the <a class="tref internalDFN" title="object_string" href="#dfn-object_string">object string</a>
+ using the pattern
+ <code><</code><strong>IRI</strong><code>></code>
+ where <strong>IRI</strong> is the value associated with the
+ <code>@iri</code> key.</li>
+ <li>If the object contains a <code>@literal</code> key and a
+ <code>@datatype</code> key, build the <a class="tref internalDFN" title="object_string" href="#dfn-object_string">object string</a>
+ using the pattern
+ <code>"</code><strong>LITERAL</strong><code>"^^<</code><strong>DATATYPE</strong><code>></code>
+ where <strong>LITERAL</strong> is the value associated with the
+ <code>@literal</code> key and <strong>DATATYPE</strong> is the
+ value associated with the <code>@datatype</code> key.</li>
+ <li>If the object contains a <code>@literal</code> key and a
+ <code>@language</code> key, build the <a class="tref internalDFN" title="object_string" href="#dfn-object_string">object string</a>
+ using the pattern
+ <code>"</code><strong>LITERAL</strong><code>"@</code><strong>LANGUAGE</strong>
+ where <strong>LITERAL</strong> is the value associated with the
+ <code>@literal</code> key and <strong>LANGUAGE</strong> is the
+ value associated with the <code>@language</code> key.</li>
+ <li>Otherwise, the value is a string. Build the
+ <a class="tref internalDFN" title="object_string" href="#dfn-object_string">object string</a> using the pattern
+ <code>"</code><strong>LITERAL</strong><code>"</code>
+ where <strong>LITERAL</strong> is the value associated with the
+ current key.</li>
+ <li>If this is the second iteration of the loop,
+ append a <code>|</code> separator character to the
+ <a class="tref" title="label_serialization">label serialization</a>.</li>
+ <li>Append the <a class="tref internalDFN" title="object_string" href="#dfn-object_string">object string</a> to the
+ <a class="tref" title="label_serialization">label serialization</a>.</li>
+ </ol>
+ </li></ol>
+ </li>
+ <li>Append the <code>]</code> character to the
+ <a class="tref" title="label_serialization">label serialization</a>.</li>
+ <li>Append the <code>[</code> character to the
+ <a class="tref" title="label_serialization">label serialization</a>.</li>
+ <li>Append all incoming references for the current
+ <a class="tref internalDFN" title="label" href="#dfn-label">label</a> to the <a class="tref" title="label_serialization">label serialization</a> by
+ processing all of the items associated with the <a class="tref internalDFN" title="incoming_list" href="#dfn-incoming_list">incoming list</a>:
+ <ol class="algorithm">
+ <li>Build a <dfn title="reference_string" id="dfn-reference_string">reference string</dfn>
+ using the pattern <code><</code><strong>PROPERTY</strong><code>></code><code><</code><strong>REFERER</strong><code>></code>
+ where <strong>PROPERTY</strong> is the property associated with the
+ incoming reference and <strong>REFERER</strong> is either the subject of
+ the node referring to the <a class="tref internalDFN" title="label" href="#dfn-label">label</a> in the incoming reference
+ or <code>_:</code> if <strong>REFERER</strong> begins with
+ <code>_:</code>.
+ </li><li>If this is the second iteration of the loop,
+ append a <code>|</code> separator character to the
+ <a class="tref" title="label_serialization">label serialization</a>.</li>
+ <li>Append the <a class="tref internalDFN" title="reference_string" href="#dfn-reference_string">reference string</a> to the
+ <a class="tref" title="label_serialization">label serialization</a>.</li>
+ </ol>
+ </li><li>Append the <code>]</code> character to the
+ <a class="tref" title="label_serialization">label serialization</a>.</li>
+ <li>Append all <a class="tref" title="adjacent_node_labels">adjacent node labels</a> to the
+ <a class="tref" title="label_serialization">label serialization</a> by concatenating the string value
+ for all of them, one after the other, to the
+ <a class="tref" title="label_serialization">label serialization</a>.</li>
+ <li>Push the <a class="tref" title="adjacent_node_labels">adjacent node labels</a> onto the
+ <a class="tref internalDFN" title="key_stack" href="#dfn-key_stack">key stack</a> and append the result of the
+ <a href="#mapping-serialization-algorithm">Mapping Serialization Algorithm</a>
+ to the <a class="tref" title="label_serialization">label serialization</a>.
+</li></ol>
+
+</div>
+
+</div>
+
+<div id="data-round-tripping" class="section">
+
+<h3><span class="secno">3.12 </span>Data Round Tripping</h3>
+
+<p>When normalizing <strong>xsd:double</strong> values, implementers <em class="rfc2119" title="must">must</em>
+ensure that the normalized value is a string. In order to generate the
+string from a <strong>double</strong> value, output equivalent to the
+<code>printf("%1.6e", value)</code> function in C <em class="rfc2119" title="must">must</em> be used where
+<strong>"%1.6e"</strong> is the string formatter and <strong>value</strong>
+is the value to be converted.</p>
+
+<p>To convert the a double value in JavaScript, implementers can use the
+following snippet of code:</p>
+
+<pre class="example">// the variable 'value' below is the JavaScript native double value that is to be converted
+(value).toExponential(6).replace(/(e(?:\+|-))([0-9])$/, '$10$2')</pre>
+
+<p class="note">When data needs to be normalized, JSON-LD authors should
+not use values that are going to undergo automatic conversion. This is due
+to the lossy nature of <strong>xsd:double</strong> values.</p>
+
+<p class="note">Some JSON serializers, such as PHP's native implementation,
+backslash-escapes the forward slash character. For example, the value
+<code>http://example.com/</code> would be serialized as
+<code>http:\/\/example.com\/</code> in some
+versions of PHP. This is problematic when generating a byte
+stream for processes such as normalization. There is no need to
+backslash-escape forward-slashes in JSON-LD. To aid interoperability between
+JSON-LD processors, a JSON-LD serializer <em class="rfc2119" title="must not">must not</em> backslash-escape
+forward slashes.</p>
+
+<p class="issue">Round-tripping data can be problematic if we mix and
+match @coerce rules with JSON-native datatypes, like integers. Consider the
+following code example:</p>
+
+<pre class="example">var myObj = { "@context" : {
+ "number" : "http://example.com/vocab#number",
+ "@coerce": {
+ "xsd:nonNegativeInteger": "number"
+ }
+ },
+ "number" : 42 };
+
+// Map the language-native object to JSON-LD
+var jsonldText = jsonld.normalize(myObj);
+
+// Convert the normalized object back to a JavaScript object
+var myObj2 = jsonld.parse(jsonldText);</pre>
+
+<p class="issue">At this point, myObj2 and myObj will have different
+values for the "number" value. myObj will be the number 42, while
+myObj2 will be the string "42". This type of data round-tripping
+error can bite developers. We are currently wondering if having a
+"coerce validation" phase in the parsing/normalization phases would be a
+good idea. It would prevent data round-tripping issues like the
+one mentioned above.</p>
+
+</div>
+
+<div id="rdf-conversion" class="section">
+<h3><span class="secno">3.13 </span>RDF Conversion</h3>
+
+<p>A JSON-LD document <em class="rfc2119" title="may">may</em> be converted to any other RDF-compatible document
+format using the algorithm specified in this section.</p>
+
+<p>
+ The JSON-LD Processing Model describes processing rules for extracting RDF
+ from a JSON-LD document. Note that many uses of JSON-LD may not require
+ generation of RDF.
+</p>
+
+<p>
+The processing algorithm described in this section is provided in
+order to demonstrate how one might implement a JSON-LD to RDF processor.
+Conformant implementations are only required to produce the same type and
+number of triples during the output process and are not required to
+implement the algorithm exactly as described.
+</p>
+
+<p class="issue">The RDF Conversion Algorithm is a work in progress.</p>
+
+<div class="informative section" id="overview">
+ <h4><span class="secno">3.13.1 </span>Overview</h4><p><em>This section is non-normative.</em></p>
+ <p>
+ JSON-LD is intended to have an easy to parse grammar that closely models existing
+ practice in using JSON for describing object representations. This allows the use
+ of existing libraries for parsing JSON.
+ </p>
+ <p>
+ As with other grammars used for describing <a class="tref" title="Linked_Data">Linked Data</a>, a key concept is that of
+ a <em>resource</em>. Resources may be of three basic types: <em>IRI</em>s, for describing
+ externally named entities, <em>BNodes</em>, resources for which an external name does not
+ exist, or is not known, and Literals, which describe terminal entities such as strings,
+ dates and other representations having a lexical representation possibly including
+ an explicit language or datatype.
+ </p>
+ <p>
+ Data described with JSON-LD may be considered to be the representation of a graph made
+ up of <a class="tref" title="subject">subject</a> and <a class="tref" title="object">object</a> resources related via a <a class="tref" title="property">property</a> resource.
+ However, specific implementations may choose to operate on the document as a normal
+ JSON description of objects having attributes.
+ </p>
+</div>
+
+<div id="rdf-conversion-algorithm-terms" class="section">
+ <h4><span class="secno">3.13.2 </span>RDF Conversion Algorithm Terms</h4>
+ <dl>
+ <dt><dfn title="default_graph" id="dfn-default_graph">default graph</dfn></dt>
+ <dd>
+ the destination graph for all triples generated by JSON-LD markup.
+ </dd>
+ </dl>
+</div>
+
+<div id="rdf-conversion-algorithm" class="section">
+ <h4><span class="secno">3.13.3 </span>RDF Conversion Algorithm</h4>
+ <p>
+ The algorithm below is designed for in-memory implementations with random access to <a class="tref internalDFN" title="JSON_object" href="#dfn-json_object">JSON object</a> elements.
+ </p>
+ <p>
+ A conforming JSON-LD processor implementing RDF conversion <em class="rfc2119" title="must">must</em> implement a
+ processing algorithm that results in the same <a class="tref internalDFN" title="default_graph" href="#dfn-default_graph">default graph</a> that the following
+ algorithm generates:
+ </p>
+
+ <ol class="algorithm">
+ <li id="processing-step-default-context">
+ Create a new <a class="tref internalDFN" title="processor_state" href="#dfn-processor_state">processor state</a> with with the <a class="tref internalDFN" title="active_context" href="#dfn-active_context">active context</a> set to the
+ <a class="tref internalDFN" title="initial_context" href="#dfn-initial_context">initial context</a> and <a class="tref internalDFN" title="active_subject" href="#dfn-active_subject">active subject</a> and <a class="tref internalDFN" title="active_property" href="#dfn-active_property">active property</a>
+ initialized to NULL.
+ </li>
+
+ <li id="processing-step-associative">
+ If a <a class="tref internalDFN" title="JSON_object" href="#dfn-json_object">JSON object</a> is detected, perform the following steps:
+ <ol class="algorithm">
+ <li>
+ If the <a class="tref internalDFN" title="JSON_object" href="#dfn-json_object">JSON object</a> has a <code>@context</code> key, process the local context as
+ described in <a href="#context">Context</a>.
+ </li>
+ <li>
+ Create a new <a class="tref internalDFN" title="JSON_object" href="#dfn-json_object">JSON object</a> by mapping the keys from the current <a class="tref internalDFN" title="JSON_object" href="#dfn-json_object">JSON object</a> using the
+ <a class="tref internalDFN" title="active_context" href="#dfn-active_context">active context</a> to new keys using the associated value from the current <a class="tref internalDFN" title="JSON_object" href="#dfn-json_object">JSON object</a>.
+ Repeat the mapping until no entry is found within the <a class="tref internalDFN" title="active_context" href="#dfn-active_context">active context</a> for the key. Use the new
+ <a class="tref internalDFN" title="JSON_object" href="#dfn-json_object">JSON object</a> in subsequent steps.
+ </li>
+ <li>
+ If the <a class="tref internalDFN" title="JSON_object" href="#dfn-json_object">JSON object</a> has an <code>@iri</code> key, set the <a class="tref internalDFN" title="active_object" href="#dfn-active_object">active object</a> by
+ performing <a href="#iri-expansion">IRI Expansion</a> on the associated value. Generate a
+ triple representing the <a class="tref internalDFN" title="active_subject" href="#dfn-active_subject">active subject</a>, the <a class="tref internalDFN" title="active_property" href="#dfn-active_property">active property</a> and the
+ <a class="tref internalDFN" title="active_object" href="#dfn-active_object">active object</a>. Return the <a class="tref internalDFN" title="active_object" href="#dfn-active_object">active object</a> to the calling location.
+ <p class="issue"><code>@iri</code> really just behaves the same as <code>@subject</code>, consider consolidating them.</p>
+ </li>
+ <li>
+ If the <a class="tref internalDFN" title="JSON_object" href="#dfn-json_object">JSON object</a> has a <code>@literal</code> key, set the <a class="tref internalDFN" title="active_object" href="#dfn-active_object">active object</a>
+ to a literal value as follows:
+ <ol class="algorithm">
+ <li>
+ as a <a class="tref" title="typed_literal">typed literal</a> if the <a class="tref internalDFN" title="JSON_object" href="#dfn-json_object">JSON object</a> contains a <code>@datatype</code> key
+ after performing <a href="#iri-expansion">IRI Expansion</a> on the specified<code>@datatype</code>.
+ </li>
+ <li>
+ otherwise, as a <a class="tref" title="plain_literal">plain literal</a>. If the <a class="tref internalDFN" title="JSON_object" href="#dfn-json_object">JSON object</a> contains
+ a <code>@language</code> key, use it's value to set the language of the plain literal.
+ </li>
+ <li>
+ Generate a triple representing the <a class="tref internalDFN" title="active_subject" href="#dfn-active_subject">active subject</a>, the <a class="tref internalDFN" title="active_property" href="#dfn-active_property">active property</a> and the
+ <a class="tref internalDFN" title="active_object" href="#dfn-active_object">active object</a>. Return the <a class="tref internalDFN" title="active_object" href="#dfn-active_object">active object</a> to the calling location.
+ </li>
+ </ol>
+ </li>
+ <li id="processing-step-subject">If the <a class="tref internalDFN" title="JSON_object" href="#dfn-json_object">JSON object</a> has a <code>@subject</code> key:
+ <ol class="algorithm">
+ <li>
+ If the value is a <a class="tref internalDFN" title="string" href="#dfn-string">string</a>, set the <a class="tref internalDFN" title="active_object" href="#dfn-active_object">active object</a> to the result of performing
+ <a href="#iri-expansion">IRI Expansion</a>. Generate a
+ triple representing the <a class="tref internalDFN" title="active_subject" href="#dfn-active_subject">active subject</a>, the <a class="tref internalDFN" title="active_property" href="#dfn-active_property">active property</a> and the
+ <a class="tref internalDFN" title="active_object" href="#dfn-active_object">active object</a>. Set the <a class="tref internalDFN" title="active_subject" href="#dfn-active_subject">active subject</a> to the <a class="tref internalDFN" title="active_object" href="#dfn-active_object">active object</a>.
+ </li>
+ <li>
+ Create a new <a class="tref internalDFN" title="processor_state" href="#dfn-processor_state">processor state</a> using copies of the <a class="tref internalDFN" title="active_context" href="#dfn-active_context">active context</a>,
+ <a class="tref internalDFN" title="active_subject" href="#dfn-active_subject">active subject</a> and <a class="tref internalDFN" title="active_property" href="#dfn-active_property">active property</a> and process the value
+ starting at <a href="#processing-step-associative">Step 2</a>, set the <a class="tref" title="active__subject">active
+ subject</a> to the result and proceed using the previous <a class="tref internalDFN" title="processor_state" href="#dfn-processor_state">processor state</a>.
+ </li>
+ </ol>
+ </li>
+ <li>
+ If the <a class="tref internalDFN" title="JSON_object" href="#dfn-json_object">JSON object</a> does not have a <code>@subject</code> key, set the <a class="tref" title="active__object">active
+ object</a> to newly generated <dfn title="blank_node_identifier" id="dfn-blank_node_identifier">blank node identifier</dfn>. Generate a triple
+ representing the <a class="tref internalDFN" title="active_subject" href="#dfn-active_subject">active subject</a>, the <a class="tref internalDFN" title="active_property" href="#dfn-active_property">active property</a> and the
+ <a class="tref internalDFN" title="active_object" href="#dfn-active_object">active object</a>. Set the <a class="tref internalDFN" title="active_subject" href="#dfn-active_subject">active subject</a> to the <a class="tref" title="active__object">active
+ object</a>.
+ </li>
+ <li>
+ For each key in the <a class="tref internalDFN" title="JSON_object" href="#dfn-json_object">JSON object</a> that has not already been processed, perform
+ the following steps:
+ <ol class="algorithm">
+ <li>
+ If the key is <code>@type</code>, set the <a class="tref internalDFN" title="active_property" href="#dfn-active_property">active property</a>
+ to <code>rdf:type</code>.
+ </li>
+ <li>Otherwise, set the <a class="tref internalDFN" title="active_property" href="#dfn-active_property">active property</a> to the result of performing
+ <a href="#iri-expansion">IRI Expansion</a> on the key.</li>
+ <li>
+ Create a new <a class="tref internalDFN" title="processor_state" href="#dfn-processor_state">processor state</a> copies of the <a class="tref internalDFN" title="active_context" href="#dfn-active_context">active context</a>,
+ <a class="tref internalDFN" title="active_subject" href="#dfn-active_subject">active subject</a> and <a class="tref internalDFN" title="active_property" href="#dfn-active_property">active property</a> and process the value
+ starting at <a href="#processing-step-associative">Step 2</a> and proceed using the
+ previous <a class="tref internalDFN" title="processor_state" href="#dfn-processor_state">processor state</a>.
+ </li>
+ </ol>
+ </li>
+ <li>
+ Return the <a class="tref internalDFN" title="active_object" href="#dfn-active_object">active object</a> to the calling location.
+ </li>
+ </ol>
+ </li>
+
+ <li>
+ If a regular <a class="tref internalDFN" title="array" href="#dfn-array">array</a> is detected, process each value in the <a class="tref internalDFN" title="array" href="#dfn-array">array</a> by doing the following
+ returning the result of processing the last value in the <a class="tref internalDFN" title="array" href="#dfn-array">array</a>:
+
+ <ol class="algorithm">
+ <li>
+ Create a new <a class="tref internalDFN" title="processor_state" href="#dfn-processor_state">processor state</a> using copies of the <a class="tref" title="active__context">active
+ context</a>, <a class="tref internalDFN" title="active_subject" href="#dfn-active_subject">active subject</a> and <a class="tref internalDFN" title="active_property" href="#dfn-active_property">active property</a> and process the value
+ starting at <a href="#processing-step-associative">Step 2</a> then proceed using the previous
+ <a class="tref internalDFN" title="processor_state" href="#dfn-processor_state">processor state</a>.
+ </li>
+ </ol>
+ </li>
+
+ <li>
+ If a <a class="tref internalDFN" title="string" href="#dfn-string">string</a> is detected:
+ <ol class="algorithm">
+ <li>
+ If the <a class="tref internalDFN" title="active_property" href="#dfn-active_property">active property</a> is the target of a <code>@iri</code> coercion,
+ set the <a class="tref internalDFN" title="active_object" href="#dfn-active_object">active object</a> by
+ performing <a href="#iri-expansion">IRI Expansion</a> on the string.
+ </li>
+ <li>
+ Otherwise, if the <a class="tref internalDFN" title="active_property" href="#dfn-active_property">active property</a> is the target of coercion,
+ set the <a class="tref internalDFN" title="active_object" href="#dfn-active_object">active object</a> by creating a <a class="tref" title="typed_literal">typed literal</a> using
+ the string and the coercion key as the datatype IRI.
+ </li>
+ <li>
+ Otherwise, set the <a class="tref internalDFN" title="active_object" href="#dfn-active_object">active object</a> to a <a class="tref" title="plain_literal">plain literal</a> value created from
+ the string.
+ </li>
+ </ol>
+ Generate a
+ triple representing the <a class="tref internalDFN" title="active_subject" href="#dfn-active_subject">active subject</a>, the <a class="tref internalDFN" title="active_property" href="#dfn-active_property">active property</a> and the
+ <a class="tref internalDFN" title="active_object" href="#dfn-active_object">active object</a>.
+ </li>
+
+ <li>
+ If a <a class="tref internalDFN" title="number" href="#dfn-number">number</a> is detected, generate a <a class="tref" title="typed_literal">typed literal</a> using a string representation of
+ the value with datatype set to either <code>xsd:integer</code> or
+ <code>xsd:double</code>, depending on if the value contains a
+ fractional and/or an exponential component. Generate a triple using the <a class="tref" title="active__subject">active
+ subject</a>, <a class="tref internalDFN" title="active_property" href="#dfn-active_property">active property</a> and the generated typed literal.
+ </li>
+
+ <li>
+ Otherwise, if <strong>true</strong> or <strong>false</strong> is detected,
+ generate a triple using the <a class="tref internalDFN" title="active_subject" href="#dfn-active_subject">active subject</a>, <a class="tref internalDFN" title="active_property" href="#dfn-active_property">active property</a>
+ and a <a class="tref" title="typed_literal">typed literal</a> value created from the string representation of the
+ value with datatype set to <code>xsd:boolean</code>.
+ </li>
+ </ol>
+</div>
+
+<div class="appendix section" id="acknowledgements">
+<h4><span class="secno">3.13.4 </span>Acknowledgements</h4>
+
+<p>The editors would like to thank Mark Birbeck, who provided a great deal of
+the initial push behind the JSON-LD work via his work on RDFj,
+Dave Longley, Dave Lehn and Mike Johnson who reviewed, provided feedback, and
+performed several implementations of the specification, and Ian Davis, who
+created RDF/JSON. Thanks also to Nathan Rixham, Bradley P. Allen,
+Kingsley Idehen, Glenn McDonald, Alexandre Passant, Danny Ayers, Ted
+Thibodeau Jr., Olivier Grisel, Niklas Lindström, Markus Lanthaler, and Richard
+Cyganiak for their input on the specification. Another huge thank you goes out
+to Dave Longley who designed many of the algorithms used in this specification,
+including the normalization algorithm which was a monumentally difficult
+design challenge.
+</p>
+</div>
+
+
+
+</div></div><div id="references" class="appendix section">
+<!-- OddPage -->
+<h2><span class="secno">A. </span>References</h2><div id="normative-references" class="section"><h3><span class="secno">A.1 </span>Normative references</h3><dl class="bibliography"><dt id="bib-JSON-LD">[JSON-LD]</dt><dd>Manu Sporny, Gregg Kellogg, et al. <a href="http://json-ld.org/spec/latest/json-ld-syntax/"><cite>The JSON-LD Syntax</cite></a> Latest. W3C Editor's Draft. URL: <a href="http://json-ld.org/spec/latest/json-ld-syntax/">http://json-ld.org/spec/latest/json-ld-syntax/</a>
+</dd><dt id="bib-RDF-CONCEPTS">[RDF-CONCEPTS]</dt><dd>Graham Klyne; Jeremy J. Carroll. <a href="http://www.w3.org/TR/2004/REC-rdf-concepts-20040210"><cite>Resource Description Framework (RDF): Concepts and Abstract Syntax.</cite></a> 10 February 2004. W3C Recommendation. URL: <a href="http://www.w3.org/TR/2004/REC-rdf-concepts-20040210">http://www.w3.org/TR/2004/REC-rdf-concepts-20040210</a>
+</dd><dt id="bib-RFC3986">[RFC3986]</dt><dd>T. Berners-Lee; R. Fielding; L. Masinter. <a href="http://www.ietf.org/rfc/rfc3986.txt"><cite>Uniform Resource Identifier (URI): Generic Syntax.</cite></a> January 2005. Internet RFC 3986. URL: <a href="http://www.ietf.org/rfc/rfc3986.txt">http://www.ietf.org/rfc/rfc3986.txt</a>
+</dd><dt id="bib-RFC4627">[RFC4627]</dt><dd>D. Crockford. <a href="http://www.ietf.org/rfc/rfc4627.txt"><cite>The application/json Media Type for JavaScript Object Notation (JSON)</cite></a> July 2006. Internet RFC 4627. URL: <a href="http://www.ietf.org/rfc/rfc4627.txt">http://www.ietf.org/rfc/rfc4627.txt</a>
+</dd><dt id="bib-WEBIDL">[WEBIDL]</dt><dd>Cameron McCormack. <a href="http://www.w3.org/TR/2008/WD-WebIDL-20081219"><cite>Web IDL.</cite></a> 19 December 2008. W3C Working Draft. (Work in progress.) URL: <a href="http://www.w3.org/TR/2008/WD-WebIDL-20081219">http://www.w3.org/TR/2008/WD-WebIDL-20081219</a>
+</dd></dl></div><div id="informative-references" class="section"><h3><span class="secno">A.2 </span>Informative references</h3><dl class="bibliography"><dt id="bib-ECMA-262">[ECMA-262]</dt><dd><a href="http://www.ecma-international.org/publications/standards/Ecma-262.htm"><cite>ECMAScript Language Specification, Third Edition.</cite></a> December 1999. URL: <a href="http://www.ecma-international.org/publications/standards/Ecma-262.htm">http://www.ecma-international.org/publications/standards/Ecma-262.htm</a>
+</dd><dt id="bib-MICRODATA">[MICRODATA]</dt><dd>Ian Hickson; et al. <a href="http://www.w3.org/TR/microdata/"><cite>Microdata</cite></a> 04 March 2010. W3C Working Draft. URL: <a href="http://www.w3.org/TR/microdata/">http://www.w3.org/TR/microdata/</a>
+</dd><dt id="bib-MICROFORMATS">[MICROFORMATS]</dt><dd><a href="http://microformats.org"><cite>Microformats</cite></a>. URL: <a href="http://microformats.org">http://microformats.org</a>
+</dd><dt id="bib-RDFA-CORE">[RDFA-CORE]</dt><dd>Shane McCarron; et al. <a href="http://www.w3.org/TR/2011/WD-rdfa-core-20110331"><cite>RDFa Core 1.1: Syntax and processing rules for embedding RDF through attributes.</cite></a> 31 March 2011. W3C Working Draft. URL: <a href="http://www.w3.org/TR/2011/WD-rdfa-core-20110331">http://www.w3.org/TR/2011/WD-rdfa-core-20110331</a>
+</dd></dl></div></div></body></html>